I'm not sure if this is depressing, or liberating.

[forsyth]

At least 90% of the time, nobody cares what you do. They won't remember. Unless you do something completely weird and memorable, or just look really freaky, most people's eyes will just glide over you. Especially on either end of retail transactions. People have enough concerns of their own, they don't have time to worry about you and what you did.