There is rarely any underlying value, but because of the hype you can still make tons of money via pure speculation, celebrity endorsements and other various types of pump/dump approaches.
It is way worse that OTC.
I think it is most self-aware scammers and the majority of the rest are naive. The only ones I've seen that are not truly scammers are those providing the platform for ICOs (e.g. Etherium, etc), because at least they are doing what they say they are doing.