So, I was introduced to a new coworker today, and she said, "Oh! I've heard so much about you. You're the one who pretends not to understand stuff so that we don't feel bad, and then explains everything!"
I gave what seemed like the only possible graceful response to that, a lighthearted, "Drat! My M.O. is out!"
Honestly, I don't think I've ever feigned ignorance to make someone feel better, although I am always very careful not to make people feel stupid for not knowing things. What's possibly not apparent from the outside is how much of my supposed knowledge is me figuring things out on the fly. I learn by talking things out, so if someone asks me a sufficiently complicated question, I usually end the conversation knowing several things that I didn't when I started.
I like the idea that I'm recognized as someone who is knowledgeable and respectful of my coworkers feelings, but a bit worried about the possibility that I might be coming across as insincere or patronizing.