In short: spam (AirBnb), cheat (fake Reddit users), and/or gamify your process to addict your users like a casino would (Foursquare). This is usually seen as unethical, but if you make a lot of money then it's all right in the end.
I'm going to take these examples whenever someone asks "what's wrong with marketing? "
I'm going to take these examples whenever someone asks "what's wrong with marketing? "