Aliens look alien to the culture they visit. This provides them with the opportunity to play god/demon/devil. This approach to cultural interaction allows for a high payoff, but is not without risks. The culture must be suitably superstitious. Note that this is not to say that it must be primitive; many technologically advanced cultures believe in the supernatural. But, to work this kind of scam, the aliens must find a suitable figure/beast to emulate and must have an advanced and subtle technology. They should watch at all times for offworld interlopers who may not approve of this sort of impersonation, or worse, are looking to cut in on the profits.