Having a good ecology of ratings and reviews is definitely important. It's probably a hard problem because you're rating people, Sasha or Adam. It's rude to say bad things about them publicly because they didn't had dishes in the sink or whatnot. Civility is important. OTOH, ratings and reviews need to convey information.

As a user, Id rather they err on the side of amateurish. Airbnb can't be the whole market. It works best for recreational travel. Even people who buy or rent to Airbnb generally do it on a small scale.