He is withholding about 1k for general wear and tear things and ventilation cleaning due "to a strong marijuana oder".

In OR, we have a bunch of marijuana guys buying grow facilities.  

If it's just drug use, especially if just marijuana, they won't do anything. 

Just as people with a medical marijuana card can be asked to avoid smoking it in a non-smoking unit, perhaps the tenant who needs an emotional support animal can look into a non-dog emotional support animal?

(Very uncomfortable) You could smell marijuana in the first unit, and the second unit was poorly taken care of.

I have friends minting money leasing to marijuana growers.  

They were OK tenants during the course, some hiccups and OBVIOUS smoking marijuana in the house with a VERY clear no smoking policy.

I agree with @Marcello Di GerlandoEven though it’s less heavily enforced these days, possessing marijuana is still illegal in some state, and if tenant's smoking is creating a nuisance, you can go ahead and speak to an attorney.

Out of my 14 tenants, all kept their employment and continued paying rent; what's more several actually secured promotions in essential industries including construction and marijuana.

Code enforcement violation There’s several Non-permitted/non-operative vehicles and marijuana plants.