I prefer a few rules to use when choosing a bounty campaign. Altcoins of the project are on some exchanges. They have a wide community of satisfied members. Dev team answers your questions about the project and is helpful in solving any problems. Has a web page, whitepaper, roadmap. The project has a real use of its coin or token. The project must offer real profits in the future /not exaggerated profits/. But it still does not have to be a legitimate campaign. So always use your common sense and take a detailed survey of the campaign you want to join. These are just a few things that should be the basis for a bounty campaign.