My gap year was at a Shell Service Station in Canberra.
It had long gone to self service, and the advice from the company was that it was for the health of us, not standing there breathing in benzine fumes for 8+ hours a day...It was pretty typical, highest selling station in Canberra, and had a shop of auto accessories (fan belts, plugs, plug leads, and additives/sealants)...and a video rental.
Toilets were outside, shared with staff, mechanics, and public. Unlocked weekdays, supposed to be locked...LOL, with a big bit of flattened PVC pipe as a keyring at 5PM weekdays (open to 10PM) and all weekend.
My job every morning after the boss got in to relieve me on the console was toilet duty. Almost invariably the women's was always the worst...everything that you can imagine written on the wall with everything that you can imagine.
Monday's in spite of the lock-up rule was always bad.
One Monday, the mens had a hand basin clogged full of vomit (coathangers help with that), a syringe, and multiple pieces of al foil in the urinal, and a coupe of used prophylactics and what looked like dried glue sitting atop the closed toilet seat.
I did my job, and cleaned it, and IIRC got the rest of the day off because it sickened my manager...that was in the '80s, the major fear factor days of AIDS, and was pretty freaky...