Nitpick time: Roaches aren't disease carriers (nor do many of them fly). About the worst they can do is transport mold around. Besides that, they're actually extremely clean. That said, I totally don't blame anyone for not wanting them crawling all over their house. (Another minor fact: Most of them don't actually breed explosively enough to "infest" a house. Buuut if you do see one in your house it probably is one of the types that do.)

The neighbours have decided to move in! D:

*the tenants.

Who pissed in your corn pops today?

Every cockroach is able to fly.

Nnnno. Not all cockroach species even have wings. Among those that do, some don't fly as adults.