The reason why the rate of scam is high in bounty is probably due to the fact that many people wants to make money by all means and do not take their time to think very well of a very legit project idea and then just come up with one and gives it a very good packaging to attract hunters and at the end crash but for you to find a very good bounty project to promote, take your time to do a very good research of the projects and be sure of the potential before you join the group.