The "sump" has gasket material to make it air tight, so there is no risk of odors. 

At least, natural gas has a super powerful odor.

When you paint the place and shampoo the carpet to get it ready for the next tenants all odors will be removed.  

Did hear some grumblings from my FIL about rent controls going into place in Carlisle.

You can't see nicotine, but you can smell odors or see smoke damage.

Took forever to get the odor out of the house, if he is decent enough to do it outside I would not complain and just keep the security deposit at the end of the lease.

Worst case scenario: Tenant didn't pay his utility bill and there are frozen pipes or a fridge full of spoiled food, some carpet is trashed, there are holes in walls and doors, and the place is full of pet hair, odor, and stains.

You can use odor blocking primer in many cases, but in extreme cases you may need to rip out sub floor. 

This why odor of mold ie mildew baby immature fungi is reduced.

#MQ5-23 Intercoastal Gray Flat Low Odor Interior Paint and Primer in OneIt was a little pricey, at 117 dollars per 5 gallons, but I believe it is quality paint and I personally like the color.We shall see if it's a hit or not!