Some examples of issues about the location that downgrade the experience:
Parking, or lack thereof. If it’s in an area where it is difficult to find a place to park, the experience is not starting off well. If I have to spend an inordinate amount of time finding a parking place, and/or I have to park a long ways away, this will put me in a bad mood.
Outside of, but in the immediate area: random person milling about. I hate running a gauntlet of people to get to a door because inevitably the people will start staring at me. I want to get to the door without having to look anyone in the eye. I’m there for a purpose, and that purpose is only between myself and the Provider.
Once inside: cleanliness. As others have said, if the place isn’t clean, the experience will not be good. Hygiene of the place is just as important as hygiene of the person.
Lightning. I don’t like harsh artificial light. Low light if artificial lighting is used, Natural sunlight is best. Of course, that would mean that the session is in the daytime and it’s possible to have curtains open and still maintain privacy (or maybe skylights).
An adequate supply of clean towels. If I’m going to take a shower, I’ve got to dry off with a clean towel. On more than one occasion I’ve seen a Provider at a hotel room incall, but no clean towels were available and the Provider would say “I don’t want to ask housekeeping for more towels because then they’ll figure out what I’m doing here.” I don’t care, have some clean towels!