He disclosed that he has a medical marijuana card but would only smoke outside. 

I would mention to Tenant B that I was visiting Tenant A and smelled what seemed like marijuana smoke coming from their side and remind them there is no smoking permitted inside the house.

2) dropping a vape in a toilet mid stay is clearly an accident.  

I won't lie - I can smell the marijuana on certain days as well. 

Handyman after guest vacates replaces toilet, breaks old toilet to find vape in toilet.  

The 4 guests smoked marijuana in the house (strong smell), broke a window blind and a picture, put a hole in the bathroom wall, chipped an end table and worst of all vomited on the couch and front porch.

Let me know what you think.As a matter of information, smoking/vaping is prohibited inside our rental units.

Originally posted by @Eric Mayer: Not sure how much Marijuana you have been around, but some smells terrible and all of that can happen without smoking it inside.

I do not care if someone had a marijuana charge 12 years ago.I do care if its 10 guys coming in for a bachelor party. 

Some cities like S.F. are even providing FREE alcohol, marijuana and methadone to these people.