Any carpet that has had a dog lying on it for 4 years is going to have body oil imbedded in the carpet, as well as odors that have permeated the padding.

It's amazing all the places that nicotine can get...like vents of the HVAC system...so cleaning may be in order.

We've found them coated in mold, nicotine & what appears to be petri dish science experiments as moisture dwells in the lower trays.

What not to like about PEX, taken from page 6 of next link:"Do not spray on or allow organic (petroleum-based) chemicals, petroleum distillates, termiticides or pesticides to come into contact with PEX pipes, otherwise permeation of harmful chemicals may occur through the pipe wall and contaminate drinking water."

Otherwise, it's a "harmless" water vapor not FDA regulated way of taking in flavored nicotine. 

If you do not like Boo Boo bear you should have smelled nicotine, and stained fingers when you interviewed the tenant.

Disputing charges for nicotine. 

Even after stripping out all the carpet and padding the urine smell permeated the house!

I simply wanted to inform other BP members to a common, albeit important, misconception that permeates this site.

In addition to these steps, I would clean the nicotine from the walls, then open all the windows and doors to let fresh air run through the house for 24 hours (or as long as possible).