Since we get a lot of snow and they won’t take their shoes off, the moisture ruined a lot of them.

A 75/25 argone/co2 mix gives good penetration and great coverage.

I've got buckled and damaged hardwoods from the moisture in the basement, 8 of the windows are as old as Methuselah,  and worst yet, the 2 car garage has what appears to be the beginnings of a sinkhole on one side. 

Also, the inspector will have a moisture meter to determine the presence of water/moisture inside the home that may have dried on the surface.

Have them bring moisture readers and test all the walls, especially if the house is older.

Tip for you who are ever on a roof placing conduit - a cinder block, held in place by spray foam and white goo, makes a great solid mounting point for mechanicals without requiring a roof penetration.   

Tenants should promptly notify their landlord when they find a moisture problem or mold growth.

What happens when the moisture in the room causes mold? 

It is important the documents are in compliance with landlord-tenant law for the jurisdiction governing your rental properties.In addition to the Lead-based paint disclosure form, for every property you will also need a disclosure about Mold & Moisture.  

If you do see some signs of "M" or mildew it is at a minimum a sign of trapped moisture.