As for ways to check legit bounties,I usually check in rating sites and I also check their list of advisors and team members.
As a newbie, you should also be aware that with ease of use with Bountyhive comes the lack of ability to verify that you’re getting credit for the work you’ve done. It would serve you more to avoid places like this until you know what to look out for. The bountyhive system is flawed because they only verify your work at the very end of the campaign leaving plenty of time for your tweets to be archived and you to get no credit. They don’t mention it until you sign up for a certain amount of bounties even though this tracking system has the ability to fail in tracking your archived tweets regardless of how many twitter bounties you sign up for. They have a severe lack of transparency and you should stay away until they work out the kinks in their system.