As far as I'm concerned, nobody is a drug dealer until the police have caught them dealing drugs. Gossip is not a good way to determine who the good guys and bad guys are. In the cases described, what's freaking people out is their neighbors being noisy and dirty and keeping odd hours. These are class and cultural differences which, I will admit, are really annoying and (I assume) strongly associated with criminal activity, but people should be held responsible for behavior that is observed and documented, not serious criminal behavior that is statistically inferred from violations of decorum. You can easily make a neighborhood more pleasant and secure by running out all the poor people, or all the black people, or all the straight people. Or the Irish. That's stereotyping. (It works, bitches! But it's wrong.)
You want to raise the tenor of the neighborhood, broken-windows style? Then use existing laws or HOA rules about trash and noise. Pass new and draconian ones if necessary. Go wild! But the police shouldn't hold people responsible for their neighbors' assumptions about them. We're supposed to be a liberal society, in the classic sense of the word. If you want to treat someone as a drug dealer, catch them dealing drugs.
If a community is splitting into two factions, the ideal would be for them to geographically separate. If a few people look down on the whole rest of the group, the few should go find a like-minded group. Obviously, "just moving" isn't as easy as one would like, but the benefit is opting into the homogeneity that some want.
If you don't like the behavior of some others, you can tolerate it, leave, or attempt to make them choose to change or leave. Communities should be small and should be allowed to have stupid rules as long as they're all willing to follow and enforce them. There just needs to be a place to go for those who don't like the rules, and going to that place needs to not be too inconvenient.
You want to raise the tenor of the neighborhood, broken-windows style? Then use existing laws or HOA rules about trash and noise. Pass new and draconian ones if necessary. Go wild! But the police shouldn't hold people responsible for their neighbors' assumptions about them. We're supposed to be a liberal society, in the classic sense of the word. If you want to treat someone as a drug dealer, catch them dealing drugs.