Read page 99 of a new book and, according to Ford Madox Ford, you'll know whether you want to read the whole thing. A new website plans to let us all try this out

Ignore Maria in the Sound of Music. Starting at the very beginning is not necessarily a very good place to start – at least when it comes to deciding which books to buy or read. Unless you are Edward Bulwer-Lytton (author of Paul Clifford, whose opening sentence "It was a dark and stormy night" has become a byword for purple prose), most writers make an effort to grab you with their first sentence ("It was a bright, cold day in April and the clocks were striking thirteen"; "Many years later, as he faced the firing squad, Colonel Aureliano Buendia was to remember that distant afternoon when his father took him to discover ice" – you know, that kind of thing) but you can't be sure of the quality of what is to follow. What starts with a bang may end with a chapters-long, drawn-out whimper.

Ford Madox Ford recommended instead that readers "open the book to page ninety-nine and the quality of the whole will be revealed to you". A new website, page99test.com, launches next month to test that premise. It will offer (courageous) authors and aspiring authors the chance to upload the 99th pages of their works and invite readers to comment on whether they would buy, or like to read, the rest.

But is page 99 a good benchmark? Applying the test to the last few books I read yields, I think, fair results too. Page 99 of Judith Krantz's Scruples (judge me all you like, I don't care) is an immediately enjoyable 500 words of frothing 80s madness. Maria McCann's The Wilding offers an intriguing letter to the protagonist, which fills in some backstory and cannot help but let you know you are in for a Right Good Read. Bleak House still fails, after 18 years of opportunities, to grip my attention. And The Code of the Woosters is, of course, perfect Wodehouse from beginning to end.

In many ways, the page 99 test makes sense. By then – between a third and a quarter of the way through most books – the characters should be established, the author should have hit his or her stride (if he or she is ever going to) and it is far enough in to allow glimpses of an unfolding plot but too early to give away any vital clues or twists.

Retrospectively applying the test is a bit of a cheat, of course. The real test should be predictive. So let's have a look – Billy Ikehorn is pondering the future in her all-white garden in California, based on the one at Sissinghurst Castle in Kent, which she visited with her first multimillionaire husband Ellis. Oh, yes – I think I'm going to enjoy Scruples Two.

• This article was amended on 28 September 2010. The original began: Ignore Mary Poppins. This has been corrected.