If they are not spayed/neutered, then there is an increased chance of odor.

Admire your old school judgement but it’s something to laugh at not something you should do anything about, or something you could even be sure of.If it’s true before long she will OD or some dude will fly off the handle.

In theory, it should be possible suck up water with a wet vac and then dry quickly with booster fans and a commercial dehumidifier (we keep a set of equipment around for that purpose) before the carpet develops an odor.

An ozone machine has been helpful for us in the past, but its effectiveness depends on the severity of the odor.

Adhering to the listing agreement solely, the way most are written, without the neighbor excluded in writing….the agreement will say agent B is owed a commission,…period.But from a practical point of view, with past and future business with developer, the agent will/should likely say…”okay, no harm no foul” since the neighbor has been in contact with the seller for years.

We do not suspect foul play because apparently that tenant's relatives have reported to the remaining tenants that the MIA tenant has moved in with another relative (but did not give that MIA tenant's new contact information). 

Are these units worth it, and have you had good success with addressing cigarette smoke odors with ozone?

Vaping doesn't produce the same strong odors or lingering smoke as traditional cigarettes or hookah, which could be a more acceptable option for your tenant.

Looking at my first property and there is a severely intense odor in the basement (concrete) and some slight orders on the other levels of the house as well (hardwood floors and carpet).

My question is, is there anything more I need to do to (i.e. issue a formal written notice of lease violation) in order to prepare for the possibility of keeping a portion of their security deposit to pay for eliminating the odor?