It's a necessity to do some research on projects before wearing their signature but what if the project is a Ponzi but the payment is good enough? When it comes to money people won't care about what they are promoting, they will promote the project and take their money.
The truth as I have said in my earlier comment is, knowing the services your employees render to the public is of utmost importance and the responsibility is placed on you as a signatures promoter to make adequate findings about the company and follow up with their feedback and development, as a signature promoter your reputation is at stake here on the forum and if the company do any wrong thing your reputation will also be placed at risk if you keep promoting them after knowing their activities as a scam.