Originally Posted by wwings

Tips generally are given as thanks for personal service.
You tip your barber because he did a good job doing something especially for you. You tip your waitress because they personally attended to your table (hopefully). 91/135 pilots occasionally get tips because of extra special personal service.

As a pilot, I graciously accept tips as rare as they might be, but asking for tips seems a bit over the top.

Unlike what Pontius said, i don't think tips cheapen the profession in any way. If a passenger/student/paying customer appreciates the job we do and wants to tip, more power to them.

We pilots incessantly whining about pay and how we "deserve" to be tipped, that cheapens the profession immeasurably.