Here's my experience: accept the Section 8 applicant, inspector comes about a week after; he's required to fail you based on one minor infraction, such as a loose wall plate, missing fire extinguisher, smoke alarm without battery, etc.

The trap was removed and it contained 1 toothbrush, 1 pen, 1 eyeliner pencil, 1 AA battery, and 2 hair bands.

Most have lights that run on batteries (a small red light showing it is on and "recording") and they even have motion ones that move in a sweep pattern.

Sometimes they've let small maintenance issues go; we find out after they move that a closet door is off the track, the garbage disposal doesn't work, some of the window blinds are broken or jammed, light bulbs not working, holes in the walls from picture frames, tub stoppers missing, smoke detector batteries dead.

They use distance sensors and algorithims to map an area so they can go room to room on the same floor.They also roll themselves back to the recharging station when the battery gets low, and after getting charged, pick up where they left off.You can schedule it to run every day, every three days, whatever.Biggest drawback is that the dust bin is a little small.

I would recommend bringing some extra batteries in case one of the smoke detectors dies before he shows up. 

A concern would be that the batteries would be dead forcing my tenants to be locked out. 

Charge rent premiums. 

Other than that, soap, some batteries AA & AAA & 9v, notepad pen dishwasher tabs a smelly candle dog treats poop bags TP paper towel a colouring book/ crayons if they have a kid some Lysol wipes and such. $20 gift certificate for pizza joint hand written “moving sucks, this may help”.

If you are in a high tech community like Mtn View, CA the tenants do not mind Cat-6, wanting electric car chargers and will pay a premium.