So you can request the proper documentation showing all of the requirements were met - they have services that will do this for you such as Petscreening.com  Still easy to fake with an online service.....just like Medical Marijuana...

Isn't recreational marijuana use legal in that state?

Oil, real estate, marijuana.  

USE OF MARIJUANA NOTICE: The State of Colorado's Amendment 64 legalizes the cultivation and possession and use of marijuana by persons 21 years of age or older.

The house was in way worse shape (including lots of moisture damage from an indoor marijuana grow), however our rehab was at a much lower finish level.  

Marijuana is illegal in the United States, period.  

I get a letter from the Tulare County Sheriff (California) stating that one of my tenants is cultivating marijuana and that I can lose the house, be fined up to $500,000 plus double the profits of the sell of the crop.

Several years ago a woman was high on cocaine and marijuana and she rode a horse head-on into a train traveling 80 miles an hour.

For example, the Feds may decide that they will start going after states that legalized recreational use of marijuana. 

If you want to stick to real estate, there was even a guy there that buys vacant land in California, builds these giant warehouses, and rents them to marijuana growers, distributors, manufactures, etc.