The best thing is old fashion wood and spring rat traps.

Set a bunch of traps and task the tenant to re-set them and put more peanut butter in them.Right now we're renting, as our house is in remodel, and the landlord is great, but it's an old house, pretty hard to seal up;  so he supplies us with traps and we work them.  

Since these are lower income people in the Section 8 program, I've been told by other landlords who participate in Section 8 that they have to be prepared to not get paid other than what the gov't pays.

This is especially true if the toilet is not on a first floor slab, but even then you don't want a pool of raw sewage being trapped under your toilet, because when you go to change or work on the toilette you will have the sewage running out all over the place.I have seen some people caulk the toilet, but not go all the way around the back so that if there's a leak they will still know.

Just when the market turned around for the worst, I was trapped with 3 houses I just couldn't find buyers for.

The problem with carpet pad in a rental is that it holds/traps liquid (water, soft drinks, beer, pet urine) that the idiot tenants are not smart enough to clean up.

If you're not in Section 8 program, Jon is on target; it was a new place, you were the only occupant, you caused the carpet to be nasty - you are responsible for that to be kept in good condition.

It's the moral equivalent of pesticide and mouse traps.

Did you check the p-traps?  

And if there is no heat and no power in winter, then you must winterize; dropping like $4 for a gallon of RV antifreeze to put in traps and to drain water everywhere else - that is way cheaper than redoing that rehab.