So I'm in Discount Fabrics in San Francisco, trying to find just the right tulle, and a stranger walks up to me. "Excuse me. Are you Patti?" I have no idea how she recognized me. Really. Maybe it was the PokerStars jacket? It was frogpyjamas
On the other hand, people used to do this even when I had what I thought was adequate protective coloration for camouflage. Back in the days when I was an aquarium hobbyist, I went to a marine aquarium conference in Miami or thereabouts. It was my first conference. Standing in the hotel registration line, someone came up to me and said, "Are you Patti?" He introduced himself, and he was someone that I'd chatted with online.
Ten minutes later, I walked into the conference room. Someone immediately stopped me and put out his hand. "You must be Patti." I recognized him from his magazine articles. Two minutes later, a third person did it. I had a pretty good idea who it was... "I'm guessing you're Deb?"
As I left the room, someone else stopped me with the same line. "Oh, you won't know me... I'm not well known."
After the fifth one in the first hour, I was a bit creeped out by it. I wasn't particularly well-known, and hadn't done anything notable besides post a few funny stories on rec.aquaria, but somehow the whole world seemed to know who I was.