I have checked the latest active bounties on bountylord.com and found many of them but only few are rated as 3 or 4 so any of you here working for any of those bounties listed there and found it trusted source of earning stakes/tokens/coins... I want to do the twitter campaign...
You should at least check the project first and the company behind it before deciding on joining the bounty. Another way is to check how n=much they have made so far to see if they are trusted by a lot of investors. With respect to the bounty, you can check if they are responsive to bounty hunters first to see that they are legitimate.
You cannot really be sure on which bounty can be trusted but you can identify which looks legitimate and has a good project. Look at the profile of the team as well. Listen to their podcast or read the whitepaper, always.