I always did just keep walking. When I would get "random" receipt checks I'd just always say, "No thanks I already paid."

Last time I went there would be a line of two or three people waiting to get their receipt checked. I walked on past and the two "greeters" (a lady and a real big guy) try to stop me. I say my line without stopping. They ask again and I say the same thing. Then a customer says, "sir sir she wants to see your receipt." I say, "Well call the police then." I left and never came back.