There is nothing nastier than to have nasty smelling poop from someone elses kids linger around your house for hours. I don't use air fresheners on a regular basis, however I do have one on hand for those days when someone lays down something so foul it gives me dry heaves. I will continue to do so, and even if this situation occured, I would explain, that in the event that it happens again, I will do something to eliminate the odor, because I have to stay in the house, she can leave quickly.
I too have had parents at interviews ask some pretty rediculous requests, one didnt like my "main daycare area" on the top level (I have a raised bungalow, upstairs is the playroom, kitchen, napping, the oly time the kids go downstairs is in the winter time to get dressed to go outside) so she asked if I could put the daycare downstairs, that way her baby has no chance of falling down the stairs!!!!! (stairs that are blocked off with a baby gate!) Needless to say, she did not become a client. I also had a parent ask me to never say "no" because it was such a negative word....I said no lol