Its pretty hard to detect perfect bounty campaigns but its not impossible too,you can rely on your own research by doing the followings
1: Do better research on the teams
Make sure they are really who they claimed to be because some scammers are stealing peoples pictires and identities on other social medias like linkedin, facebook or twitter to fool investors and rob them of their money

2:the usefulness of coins and tokens is what makes them become valuable in time,dont promote bounties with no real use case or working product

3:Make sure the project roadmap consist of good future updates which is another good info of short term profits or ROI if you investing,if better upgrades are available for project it will easily add more value to the project coin or token