I check for signs of plumbing leakage in the kitchen and baths and do a visual inspection for any noticeable damage.  

Risk of leakage, breakage, humidity, etc...  

Now if it involves cleaning out a sewer line or locating a pipe leakage inside a wall or underneath flooring, that's when a you call in the licensed professional.  

If you keep giving them 24 hour notices to enter to check on what the cause is for the electrical "leakage" or whatever, and they keep having to dismantle and relocate their little grow operation, they may just get rid of it or move it somewhere else.But, that's my guess.  

You don't necessarily need to go that far, even a 4-6" "topper" of blown cellulose will greatly reduce air leakage into the attic & that's what you and your tenant both want.  

Or is there an inspector or someone that can check the duct work or air leakage?

As for the duplex, the bottom floor of the duplex has been completely gutted due to prior leakage from the top floor.

I heard that can cause financing problems.In digging further the litigation is from a single person complaining about not being treated well by HOA regarding roof leakage repairs.Should I still be worried about financing issues?

That's too much leakage for me to be happy with.  

I make them look nice by framing around the inside with 1x2, putting rigid foam insulation in and covering with bead board, caulk and paint and they look great and eliminate the air leakage from the cheap accordion fillers.      500 bucks and an hours work versus 6-8k.