'Pod rerkoomayndarmer algoonsh pratoosh rerzhyoonighsh?' I ask hopefully. The waiter smiles with the air of one who has suffered much and turns on his heel. Moments later, he returns with a menu in English. 'The speciality is grilled sardines,' he says. I hide my Portuguese phrase book under the table. 'OK, I'll have that.' And then, inexplicably, I order a glass of white wine in Spanish, but with a French accent. That'll show him.

He returns with a huge carafe of wine. My dilemma: whether to explain shamefacedly that I only wanted a glass, which he would have understood if I hadn't tried to show off by speaking Spanish, or pretend I meant to order it and drink the whole carafe. I decide the latter is easier.

Having just spent a weekend in Lisbon putting a handful of Portuguese phrase books through their paces, I can confirm that, where foreign languages are concerned, a little bit of knowledge is a dangerous thing. Apart from anything else, there is something fundamentally naff about using a phrase book. Like guide books, cameras and sunburn, they confer on the user an instant badge of shame: 'Look at me everyone, I'm a tourist.' Surely it's better to be lost and misunderstood than causing patisserie queue rage as you insist on looking up the word for custard tart.

You can try to get around this by secretly swotting up on a few key phrases and keeping the book out of sight, but even this can backfire horribly. Before joining the ticket queue in the metro, I rehearsed: 'A return ticket to Oriente, please', only to be told in Portuguese that this particular metro line was still under construction (though obviously I didn't understand this was what he was saying at the time).

By the time you have looked this one up in your phrase book, a) you will have been lynched by an angry mob, b) the man behind the counter will have pulled down the blind and gone home, or c) if you are really lucky the line will have been completed. The moral of this story: speak perfect Portuguese to people and they will answer you in perfect Portuguese, which is not much good if you can't speak the language.

Still, you can't help but be touched by the optimism of the publishers who hopefully throw in chapters headed 'Making friends' and 'Socialising'. Who are they trying to kid? If you have to look up the words for 'I'd really like to see you again' then it's unlikely your sparkling repartee will have won you a second date. But if you do get lucky, Lonely Planet boldly goes where no phrase book has gone before, with a section on the language of love from 'Oh baby, don't stop' (which seems to rely on the dubious premise that you have your phrase book to hand at all times) to 'Why don't we live together?'

I suppose we should be grateful that most phrase books have finally acknowledged that our holidays don't revolve entirely around the bus station or the grocer. But the content of some of the books tends to be a bit hit and miss.

Dorling Kindersley's phrase book won't help you if you get your passport stolen but there is a whole chapter on getting your hair done at the hairdressers. Lonely Planet won't give you the Portuguese for contact lenses, but if you want to swear at your newfound foreign friends, then it has a few ripe insults. My favourite is: 'Vai pentear macacos!' which translates as 'Go comb monkeys!'

However, should you find yourself in a sit uation with someone who genuinely does not speak English, phrase books can have their uses. My Berlitz phrase finder came valiantly to the rescue when I realised there was no bottle opener in my minibar. The cleaning lady mistook my bottle-opening mime for an impersonation of a one-winged chicken but I managed to look up the word before she rushed off to maim some poultry.

And they will all prove invaluable when you need to look up that most useful phrase of all: 'Do you speak English?'

How we judged the books

To test the books, we chose 10 different everyday phrases that a traveller might need to use - for example, 'My room is too noisy. Can I move to another one?' and 'Where is the nearest beach?' - and gave each book between 0 and 3 points depending on how quick and easy it was to find a suitable translation for each phrase. The maximum score available was 30.

Berlitz Portuguese Phrase Book & Dictionary £3.95

First impressions: compact and colourful. Little icons on each page make it easy to find your way around. There is a concise, and very necessary, introduction to the many peculiarities of Portuguese pronunciation but no separate grammar section. Individual chapters are prefaced by useful local information.

On the road: detailed and well-thought-out contents page makes it easy to turn to the right page first time. More than 30 pages on food and menus and culture vultures will love the tourist glossary which is full of useful historical and architectural terms.

Score in the phrase-finding test: 21/30

Best phrase: What's the pollen count?

Verdict: ****

Very user-friendly and a more comprehensive dictionary section than most other phrase books. Dabbles in small talk, though more coy than Lonely Planet (Heck! is as strong as it gets in the rude word department). Excellent food section makes it a good choice for gourmet travellers.

Dorling Kindersley Portuguese Phrase Book £2.99 (£5.99 with cassette)

First impressions: slim, lightweight book, attractive cover but slightly dull inside. Comes with a 90-minute cassette of words and phrases to help you perfect your pronunciation. No grammar content but there is a brief explanation of the main differences between European and Brazilian Portuguese.

On the road: contents page reflects the skimpy content and it's difficult to know where to look for certain topics. For example, beach vocabulary (I would like to hire a sunshade) is listed under sport. There is hardly any vocabulary related to sightseeing, culture or socialising, yet there is a whole chapter dedicated to At the Hairdresser. The dictionary at the back gives only English-Portuguese translations, not vice versa.

Score: just 6/30

Best phrase: A bit more off here please

Verdict: *

Surprisingly bad unless the highlight of your holiday is getting your roots touched up.

Lonely Planet Portuguese Phrase book £4.50

First impressions: attractive, pocket-sized book; different coloured text makes it easy to read. The opening chapters deal comprehensively with the peculiarities of Portuguese pronunciation and grammar and would make a good introduction for somebody interested in learning the language.

On the road: the easiest to use of all the phrase books reviewed. Excellent and detailed contents page means you can usually turn straight to the page you want. Includes a guide book element with useful snippets of information on local culture, social issues and etiquette. Has some quite specialised vocabulary (for example a section on gay travel) which is not featured by other phrase books.

Score: 19/30

Best phrase: Let's do the Mexican Wave!

Verdict: *****

If you want to discuss politics and social issues, your drug addiction, sexual preferences and Black Magic, this goes where other phrase books fear to tread. Though it didn't score quite as highly as Berlitz or Penguin when it came to looking up everyday phrases, it more than compensates with its breadth of content and it's the most fun to use.

Penguin Portuguese Phrase Book £5.99

First impressions: this book was first published in 1971 and seems to be sporting the original cover design 30 years on. Inside, the typography is messy and amateurish, and it's the bulkiest of the books reviewed. The chapter on pronunciation is particularly hard work.

On the road: proof that appearances can be deceptive. This book was surprisingly easy to use and managed to come up with exactly the right phrase, quickest, virtually every time. The chapter on hotel rooms gives no fewer than 40 different complaints.

Score: 27/30.

Best phrase: I will X-ray your teeth

Verdict: ****

A mind-boggling selection of phrases for almost every situation. Serial complainers and fussy travellers need look no further. Other phrase books might tell you how to ask where the beach is. Penguin will give you the words to ask if it's pebbly, sandy, quiet, safe for small children and whether the tide is rising or falling. Drawbacks: there is only an English to Portuguese dictionary. It's a bit square, in shape as well as content.

Portuguese: The Rough Guide Dictionary Phrase book £2.99

First impressions: rather than divide vocabulary into situations (shopping, health etc) Rough Guide has opted for an alphabetical dictionary of key words, interspersed with dialogue boxes for commonly used phrases and lots of local information. The Basics chapter deals with the nitty gritty of pronunciation and grammar.

Ease of use: Rough Guide has tried to do something different but I'm not sure how well it works. The dictionary format is tedious and time-consuming. If you want to ask: 'Where can we hire a surfboard?', you have to look up at least three different key words and will probably end up cobbling together sentences like: 'Where hire surfboard?'

Score: 14/30

Best phrase: Hey!

Verdict: **

This has by far the most comprehensive vocabulary of all the phrase books but unless you have a basic knowledge of the language you could end up sounding like a caveman.
Buy it at BOL