It's my personal opinion that Magicians shouldn't work for tips. Get your money from the Restaurant, not the customers.
I feel if you work for tips, you are hindering the performance. They want to be entertained, and already paying for a meal. The last thing they want is someone saying "gimme gimme". Whether it's stated or not is irrelevant. If it's implied, you've risked the joy of the magic.
I understand where you are coming from, Dan...but I don't necessarily agree. I work for tips at my restaurant, and honestly I feel fine doing so. I don't feel it hinders my performance at all (and trust me, I am fanatical about having a stellar performance). I feel that people pay for all sorts of other entertainment, and what I and other magicians provide is an entertainment that is not easily found...and, if the magician performs well, should be tipped.
Cmon, if Im going to tip waiters for bringing my food out, or grocery baggers for bagging groceries, I certainly will tip a magician. They are all (in most cases) being paid by their establishment, but the tips make what they do more worth it, and is a sign of deep appreciation for their service. I find nothing wrong with that.