It is a little more work but after remediation, and proper ventilation, a good coat of Kiltz or a similar stain-blocker not only hides the stains but does wonders as a future barrier and helps mitigate the smell.

This deal smells on so many different levels and if it were me, as others have rightfully suggested, I'd pause and renegotiate on all terms.  

Because it's so soon, I'm not worried about the fact I smelled weed in the unit despite the *ABSOLUTELY NO SMOKING* in bold print on the lease.

Same thing in the neighborhood I grew up in, a bunch of busy-bodies who like to harass their neighbors for contrived grievances.After those experiences, I cannot imagine buying in a neighborhood like that, especially if I'm not going to live in the house.

You might even have to install specialized ventilation systems to keep the smell down (Denver has a Department of Environmental Quality that keeps on top of this...though you can still smell it when you drive by).  

Any body have any solutions?

If you find any infractions after performing item 3, such as obvious evidence (smell or other) of smoking of any kind, start the eviction process according to your own lease terms, with careful attention to landlord/tenant law in your state.5.

The ceiling had maggots and smelled nasty due to the upstairs dogs pissing into our ceiling causing the intermittent leaking (no pipes in the area, and its dark yellow liquid that smells bad).I have called our insurance who have said that since maggots were growing, its been like that a while and they cannot do anything and to contact upstairs neighbors insurance.

Paint a mural on the side facing you.Next, buy adjacent to a hog farm and complain about the smell.

Is the broker kicking them a salary or is the owner just churning through warm bodies to drive investors around?