Generator inspections

Anyone out there that does generator inspections, are there any red flags or things you have seen in the field that you have found to be deal killers? Just want to be ahead of the curve for our clients that may be selling their homes. Thank you.

The biggest thing I run in to is the lack of any permit sticker. Probably 80% of the time they have been installed without permit.

Signs. I see missing signs on many jobs. Signs are required by the NEC to be on or at the service equipment.