You yourself had answered why you got scammed ? 15 projects in a year must be too much for the any kind of investor or for bounty participants. I'm not sure how you have chosen them but you was rushing for projects that must be the core reason why you got scammed. Please take time to have list of checks and analyze the projects to short list them and then go for anther round of analyzing and finally on your satisfaction, start working for a project.

OP is not asking any direct suggestion but asked for how to find out the good projects. I doubt that you might be a paid advertiser of your recommendation. Due to people like you, this kind of discussions are not growing up to the level it should have been. Please do not refer for your benefits and also do not detail the purpose of the topic.