I saw a graph of the English betfair market since it began. The only thing it was good for was that it showed that layers were doing no better or worse than bettors. Anecdotal evidence aside, basically it's dead even between them. As a guide to which horse to back, it's probably no better than watching price fluctuations on a tab screen. Meaning horrible.

The best guide I think to which horses you can make money on is always a very good form guide, stewards reports, gear changes [and knowing what they mean], etc. etc., learning how to use all that info. profitably and ignoring everything else, especially media tip prattle, horse or trainer promotion and short price firmers and backing your own opinion even if it's drifting in price badly! Not as easy as it sounds, I'm still trying !!