I have not gotten a blank check from the first timers that aren't home.
Usually we both agree to do a credit card over the phone before I leave the job, giving them a end-of-job report during that call.
Yes, have gotten garage codes and "the key is in the flowerpot" custys.
Some repeat custys I have never met yet. Maybe never will.
Just gotta be EXTRA thorough in these situations.
Do a final walkthrough, and imagine you are them, coming home to inspect the job.
Everything must me triple-tight.
Over do-it on the scent/deodorizing.
These are sometimes the same folks that leave little notes, or yellow post-it tabs in the concerned areas.
One time, while working for another company, I was sooooo hungry, I helped myself to a M&M bowl, in the entryway, and was paranoid for a week that I'd end up on some "caught-on-tape" show, wolfing down M&M's that weren't mine.
God those were good.
Never again.