I'm assuming he's busy creating the vaccine for Corona using the discarded cigarette butts and hypodermic needles of his tenants. :-)

My tenants are having a long standing conflict, the people upstairs are smoking weed outside of their window, and the smoke is drifting into the windows of the people downstairs.

Up here, I am hearing from closing attorneys that no cities are performing water readings, smoke inspections, etc... and appraisers and home inspectors are not moving either...I can only imagine the Housing Authority...I would generally plan on at lease 1 months elapsed time with a Section 8 tenant under NORMAL conditions. 

Stopped smoking (I’m sure someone will rip into me for suggesting that one)?

One person has a dog (Spaniel) and I believe he smokes as well.

I agree that you should move the smoking space elsewhere.

Offered full price + $5300 in repair credits (the current tenants smoke, so I'm thinking repaint + refloor + install new HVAC, which is unrelated to the smoking) and the seller will pay $1300 of the closing cost.

There's been no issues over the last 10 years except for the guy who had ex-cons who smoked the last few days, just to stick to the schedule.

The biggest problem with MO is first off smoking rates are decreasing world wide.

Unmitigated water damage becomes mold damage and and there is the potential of extensive smoke damage in the same airspace.That's a quick run-down.