The situation goes like this. Lots of excellent, capable people have great ideas for new software products. They are bootstrapping their venture, so they look for a developer who wants to give some time up front and receive a fair (let’s assume fair) share of the rewards once the product becomes successful.

The question is: as a developer, how do you know which of these products (I get about one tempting enquiry a month from what sounds like a real person who isn’t building a social network) is a good bet?