well, this is something that is not easy to detail. Some aspects, like the product/useability of the project, the team and the structure are base for trust, but there is also a subjective element to this evaluation, as sometimes things seem good, but trust doesn't come naturally, sometimes the energy/support shown on the social channels, or the way the team deals with some questions or the way it choose to solve certain problems are "trust killers" as they show a poor capacity to manage the project...
Trust has to be earned... it is not only a matter of analisys (especially with all the scams/newbies around)