As they are still fairly new, regardless of what the WHO states, there just has not been enough studies to definitively prove long term health effects.That said, prolonged vaping can leave an odor in the home because those vaporized oils have to go somewhere.  

Besides San Diego, I'd wondered if there would be newer investors who hadn't set aside reserves or just someone who had been aggressive and overextended and who would need to sell after not being able to handle the prolonged vacancy.

On the other hand, academia can function as a prolonged adolescence for many people, and I know many very well educated people who struggle financially (read some of Robert Kiyosaki's books for a much more in depth discussion of this phenomenon).TL;DR if you want to go to school for its own sake and you can do it without putting yourself into massive debt, do it.

They have expanded the life of the scheme by prolonging the payout time to investors - most of the typical pyramid scheme return investors promised amount in a lump sum in a shorter period of time thereby giving out more cash and increasing the cash stream problem.3.

However, they were a "Professional Tenant" and that only prolonged the eviction process in their favor.

I appreciate you giving advice on delayed financing and it is something I might do in the future when my cash flow is higher to cover any prolonged vacancies.

Studs, with prolonged exposure, can develop mold colonies, and metal (like nails and screws, metal bathroom fixtures) will rust.

I will not invest for appreciation in such a manner as to have negative cash flow for any prolonged period of time, however. 

According to Investopedia:“A recession is a significant, widespread, and prolonged downturn in economic activity.

Assess your comfort level with the potential downsides, such as prolonged negative cash flow or slower-than-expected appreciation.