Unfortunately, bounty participation always mean risks to lose your time and money (as you cold spend this time on other projects). Sometimes, the projects can't reach soft cap, and you risk not only on scams. The only way is to go on, and believe that best is yeat to come.
There are also times when a project does not even complete. Its possible that while the project is ongoing, its developers and team will suddenly disappear. Some ICOs are made solely for the purpose of gaining profits and once money has been made, the scammers will be gone. Its definitely a disadvantage for the bounty hunters who spent their time and effort participating in the bounty campaigns.