This has only happened to me once. I had been shooting my shen hao for about 6 months, and I got my first ITAH. I was surprised at the question, so I gave a very candid answer, "I don't speak Chinese. It is a 4x5 camera." She walked away very confused.
After reading the first few pages, i'm getting the idea it happens a lot. I'll think of something more cynical the next time it happens to me.