"Uh....well my aunt says we can't sleep on her couch anymore."  

Maybe find out what they need help with, what is stressing them out, what is hard on them and keeping them from sleeping... see if you can add value... see if you can be helpful to them.

They pretty much just use the rental to sleep and eat. 

They're too exhausted to party, and they basically use the unit to sleep and eat. 

You start to feel sick because it is so hot, you can't sleep because it is so hot.This time of year wouldn't be nearly as bad, but still. 

If not, schedule a maintenance inspection, see if anything else looks like it might need attention, and try to get a read on what is really going on there.We did have one tenant who only had sleeping bags, this was their work location rather than home base; it does happen.

., and basically use the unit to eat and sleep, and sometimes study in.They also will very likely stay several years, if you can target 1st year law students (or med students).This can be done by finding out how to advertise in their departments at the college. 

Even if they reported it, they can deny it, then blame the seller, then the seller blames them, then someone blames you, then you and your wife can't sleep at night because it's so stressful with all the finger pointing and potential lawyer junk fees to sort it out over a couple hundred dollars....Once the place is vacant go in and fix everything to your standards and start new.  

Personally, unless there were sleeping bags all over the place and little children crayon marks all over the walls, I'd turn a blind eye, with cautious awareness. 

I wouldn't lose sleep over this tenants complaints, but I would surely not renew their lease.