This can be tricky and is likely something you have discovered already; not all 'money-making' apps are legit, and there are scams. The key is to check how many users the app has, what sort of ratings it possesses, who the developers are, and to look at reviews about the app.  Often the scam apps will have very low user counts, and they are there to make a quick buck off of those who fall for the scam by having them watch countless adverts and having incredibly high minimum withdrawal amounts.  Usually, an app that is not paying out to tons of users and only has a few good reviews is probably a scam. Do not be fooled by a few good reviews, as they are probably false or paid individuals who are there to entice other people to use the app.  It is crucial to see who the developers are; look at what other apps they have made in the past and what their user count and reviews are for those. Usually, a well-established company is one that is legit, because if they were a scam, people would have caught on eventually.