In the future, make sure language in the lease addresses this.You want to avoid having a tenant work on your property for a few reasons: The work may be done poorly and you'll have to redo it; the tenant may become injured doing the work and bring a lawsuit against you; it muddies the waters of your  existing relationship.The most I allow my tenants to do is change out the smoke detector batteries if needed- even that is in the lease.Good luck!

This problem was brought up in another landlord forum, the landlord dealt with it by disguising the cameras in smoke alarms, fire extinguisher boxes and exit signs.  

No Pets, No Smoking, Section8, etc. 

You want to change the parking rules, or late fees, or smoking, or anything - 30 days notice.And, tenants can't hold you hostage ever, knowing you can't kick them out until the end of the lease - or at least without major hassle.  

People can look years older than their age due to smoking and other poor environmental situations.

It doesn't have to be Secret Service clearance, but you should have at the very least a set of written policies (no smoking, no pets, cut the grass, whatever) about the unit, an application & credit/background check policy (minimum income level, employment, etc), an eviction policy, and a maintenance policy.

I told him I wouldn't pay because at closing I was asked if there were smoke alarms in each unit because if not they seller would have to give me an additional concession of $250.  

So maybe some new tech there but I would be surprised.I would even put yeast down the toilet every time I changed the batteries in the smoke detectors. 

Anyway, within a few minutes, smoke was pouring out and filled the air.

The biggest risk is not really from a physical damage, but more of a "pet smell" like smoking, that would cost you a new paint job or carpet (although a 80 lb lab could shred hardwood floors, to).