Could be as small as a dead battery in a smoke detector in the middle of the night (no guest wants to hear beeping while they are trying to sleep), guests can get rowdy and disturb neighbors, I have even had guests that insisted upon having someone meet them face to face when they arrive.

I recently visited a multifamily property with over 210 units and one of the main issues was the smell of smoke in the units.

Get a smoke alarm connected directly to the furnace 3.

check smoke alarms and carbon monoxide detectors. 

@Andrew Dao My man, that is a smoking house, great photos!!! 

Hello,Long story short:  Tenants didn't pay last month's rent and damaged carpeting with smoking (prohibited in lease) and other stains, left significant junk to be cleaned out and some other damages. 

@Jason SpicerI had an apt unit where a guy lived and smoked in for 20 years.

Just seems like a win win situation, no foreclosure for him and I get a smoking deal.Any advice or guidance would be much appreciated.

Some of them smokes, turning on appliances and air condition.

Smoke and/or grease residue from smoking or cooking would also not be normal wear and tear.