It is legal to have a pet and it is legal to smoke cigarettes.

Such as smoking and leaving a cigarette out which burns the house or some unfortunate accident.

Do not accept a smoker-- not even an outside smoker.

There is a lot of damage however.There is a large number of cigarette burns in the carpet and there are many stains on the carpet throughout the unit.

If there isn't a smoker upstairs and something happens, then you could be sued based on previous warning by the tenant.

The building was fully rented and three of the tenants are long term renters and smokers. 

I walked the property today and found several cigarette butts. 

Appliances at per hour rate Window cleaning, tracks, at per window rate, A/C filter cleaning / wash it 10.00Bath tub at hourly rate Key replacement, lock replacement, mail box key, remote control.Glass and screen repair as per item Carpet Cleaning extra spot removal, cigarette burns, pet odor Sheetrock repair, nail holes starting at 15.00 per roomNicotine smoke or grease smoked walls, wall wash, kilz primer per room charge, extra for ceilings.Any furniture left per item, list couch 45.00, chair 25.00, mattress 25.00  plus labor to move.

(think smokers who are told in the lease to not smoke in the house). 

At least not around here, per my understanding from several different sources.It is pretty common for people that are on section 8 to have bad credit, have no job, have (often weird) pets, are smokers and no ability to get a security deposit.