Another tip into finding a good bounty is knowing the participants. If you see that there's a member that is quite good on this area joining the bounty, you might as well follow the path. Sure we can trust ourselves by identifying which bounty is the right one, but we can also get another set of eyes to look upon it. Another member that is more professional on this matter has a low possibility to join in a scam. That is why we can at least be more sure on what we're about to join.

Although, the downside of this method is that we can't fully trust other people because they could make mistakes just like we do. Even though it is indisputable that a professional member would have already known those 5 tips that OP has mentioned, but they might forget one thing or two and end up being in the wrong direction. After all, we're all only human.