Bounties merit is you gain knowledge and represent a project in professional way it is positive gesture for your account and the demerit of Bounties is scam projects if you unable to select legit project then scam project will destroy your efforts and wastage of time at the end you will get nothing.So it is strongly advised to be careful choose the real projects to save your time and efforts.
I agree you need to very carefully check projects and study them because, because you choose the wrong project, its not enough that you lose your money. So, even by wasting your time on working better, have people who know where to invest in this business.