Even if the specific booking is not from Airbnb, the entitlement is permeating the market in general.I do like how pretty much all of the OTA's offer trip insurance. 

Wage growth is still running at over 4%, above core inflation.This permeates to all workers, including the construction trades, and thus, to the price/cost of homes.

If they were smoking outside, the odor would quickly dissipate and would not permeate the building envelope and infuse into the other units. 

The smell of cat permeated the house and my mother said we had no mice in the house that year.Does the fact this mouse was found dead make a difference?

Additionally, all odors and smells now permeate the entire house, for good or for bad, and the same goes for moisture, grease, etc.

The influence of the global economic slowdown permeates from localized markets such as Bakersfield, California, to the expansive horizons of the United States and beyond.

And remember, CPI of nearly everything is higher every single month, which permeates into materials, services etc… that are necessary for building / renovating homes.

A body smell can permeate walls, cabinets, wood, cement. 

In 18-months the damage will be somewhat limited and {hopefully} will not have had the opportunity to permeate the subfloor and structure {though that is a possibility} - you may just get away with a lots of cleaning and replacing finish flooring (like carpets).The longer they stay, the more expensive the repairs will be at move out.

In-ground tanks can leak for years and years and no one notices until lots of oil has permeated the soil.