I can say 100% that 60% of all bounty is a Scam. The reward for them is either given and the tokens will lie on your wallet forever or do not give at all. Then what's the point of doing this ?
This is a new business without borders. Of course fraudsters use this But I do not think that all projects are like that. Perhaps just lack of funds affects the project. Or an unstable cryptocurrency market. The saddest thing is that fraudsters learn too. And every day to distinguish scam from a good project becomes more difficult.