Bounty is hosted with ICO, to know how to differentiate the True/Legit and scam is paying attention to their platform. Like asking yourself, what is their platform? What their platform is going to solve? If your nswer will satisfy yourself, then it is a right tim to make conclusion.
For example you will know what is legit and scam through this.
1. Sketchy looking website.
2. Team is anonymous
3. Their vision and missio /roadmap.
4. The ambience.
5. White paper
If that could give satisfying answer, assuming they are legit, when There's still question running through your mind, and it gives you doubt, try to search about the reviews. If the ICO is legit, surely their bounty is!
I hope it helps.
It not always works in fact. I mean right now on ICObench we have a campaign with very high rating and big team also ranking at 4.8.
But... in fact its CEO and second person was marked KYC FAILED. It means they couldn't provide their real ID and themself verification