I was thinking about this the other day when I filled up. I took off my helmet, although I often don't.
In the old days, a gas station attendant might have looked suspiciously at a biker who hid his face while filling up, suspecting a pump & run, but with pre-pay at all stations now, there doesn't seem to be any reason to remove your lid if you're in a hurry.
Yes, it is a slow day at work, and I'm bored. How could you tell?