High power motion detector lights in the back yard. 

Could be as small as a dead battery in a smoke detector in the middle of the night (no guest wants to hear beeping while they are trying to sleep), guests can get rowdy and disturb neighbors, I have even had guests that insisted upon having someone meet them face to face when they arrive.

check smoke alarms and carbon monoxide detectors. 

Did the HVAC guy physically show you a leak with leak detector?

Gfi around sink  , peeling paint, carbon monoxide detector, smoke detector and other common sense type things.  

Of the 3 houses I have purchased so far, we spend $3,000 on the first house just doing small stuff like light fixtures, ceiling fans, smoke detectors, and various minor repairs.

Carbon monoxide detectors were not observed in the home.

This kind of stuff aside, I include the following clause in my lease:SECURITY NOT PROMISEDThe Tenant has inspected and acknowledges that all locks and smoke detectors are in working order.

I didn't previously consider LED's and motions detectors.

Just want to make sure you are aware of the new Smoke Detector law going into effect this April.