Its like anything else, you hide the bad and sell people on the good. Or if there is no good you talk as little as possible. Could they guess its a scam job beforehand? Probably, but they have to see an opportunity through and by the time they know for sure they are comfortable in their job.

People are acting like America has no scam companies. They are literally in every city, I almost worked for one when I was younger. MLMs are the most common example people would know about.