Otherwise, it's a "harmless" water vapor not FDA regulated way of taking in flavored nicotine. 

Fog, boric acid or that combat gel around all the base boards, treat perimeter.

We used a gel stain on the kitchen cabinets 

Get one of those rust removing gels to really get the rust off.2.

Okay met the bug guy today at my complex.He said the problem I have is German cockroaches.Stated tenants have to stay clean or bug problem won't go away and that all tenants have to be clean or bugs will spread to other units in the building.We are going to be doing inspections to the units once a month.If tenants are not keeping clean I will file for eviction on them immediately.Bug company wanted a crazy amount 500 month for 20 units in 5 buildings.What I ended up doing is one building at 100 a month.This building had tenants I just got out and the unit was really bad with roaches.Said one of the worst he has ever seen.The other 4 buildings have no current bug problems that I know of.I know I can buy Boric acid and the gels myself but if you would have seen this unit you would gladly pay the money.Bug guy said after a few months I could save by going quarterly and I can cancel anytime.I also didn't want the liability of putting down pest control substance in tenants apartments and wanted to leave that to the professionals.Any comments appreciated.

If you do not like Boo Boo bear you should have smelled nicotine, and stained fingers when you interviewed the tenant.

Disputing charges for nicotine. 

If you end up keeping one unit as an MTR, move out of the other and put a family in there, your mix of tenant types might not gel.

All it takes is one single nibble from a mouse / rat and it starts to get very thirsty, they then go outside looking for water & die outside as their blood starts to gel.

My lease says it is the tenant's responsibility, however, since I mostly own small multis, I keep Advion gel bait pucks for roaches, a get bait pucks for ants, and fast blox with tamper proof bait stations for mice on hand and give them out for free.