I knew several living in regularly middle class neighborhoods with regular clean houses. One, in a gated community.
I think it's just as equal chance as anyone else having a messy house. The news rather shows sensation, so I think they would be less likely to give a tour of the drug dealers house if it looked like it could be your neighbor.
Also a lot of times people who deal drugs do it as a last resort. People who are already down and out. So poverty to begin with and everything that goes with it.
Poison is in the fangs not the meat