When I first started using airbnb, I would run into these awful listings because I was scraping the bottom of the proverbial barrel.
On a visit to Boston, I once stayed in a cheap AirBnb in the bad part of Methuen, MA, where the local grocer knew I was from out of town because I paid in cash and not food stamps.
My wife, on the other hand, always reads the reviews and I've never had a single bad experience travelling with her.
If you go by price you get what you pay for. This isn't a failing of AirBnb, its how life works.