I suffer from back pain. Fortunately, I've not needed a scooter on a cruise, yet. I once rented one going to Disney. At one point I got stuck in the middle of a crowd with nowhere to go. Fortunately, someone else carved out a path for me and another scooter user. I only lasted two days before returning it.
My point, you wouldn't know looking at me if I was a scooter rider if I needed it or was faking it. Back when muster drills were done on deck, I'd go to the handicapped area since I can't stand, packed in, that long. Heck, the first time they saw me coming a little hunched over and directed me there without me saying anything.
I try to be courteous to those in a scooter. I'll hold the elevator, etc. But for those that decide just bumping into me will get me to move versus a polite "excuse me", all bets are off.