You've saved your tenants asses. Lazy people harm others.  Spread crumbs everywhere, never cleaned, etc. = B. Germanicus cockroach infestation.  B. Germanicus being the small semi-rectangular cockroaches, half an inch long, that are far worse than even other pest species (like the larger and scarier-looking American Cockroach and Oriental Cockroach) and very hard to exterminate.  It's one thing when it's an isolated house, but when it's an apartment complex, the other tenants are fucked.