The site would step up if you add in a scam section where some of the projects have been busted as a scam will be listed there. I think that will be helpful for everyone and is a good prevention tool for newcomers to avoid that project. If you aren't in favor of that I guess just giving the projects an icon/status logo where it will indicate as a scam is another helpful addition for your website. Also prevent adding ratings entirely where you or the users will be giving ratings for the said project as it will most likely be biased or be used the wrong way by others like what popular sites are doing now.