I have received tips, occasionally, over the course of my career. Usually it has been a bonus for a job well done when a client stops training with me for whatever reason.
That being said, I never expect a tip; and the best “tip” I could receive is a referral which shows that I not only did a good enough job for them but they trust me with others as well 🙂
At my studio, it is my business and profession. I am a highly educated and capable instructor. I charge fees that are in line with the fees and abilities of our profession in my area. I do not accept tips.
If I were working for a resort or gym, sure I would accept tips as a form of appreciation from the customer/client. But in my studio, no tips for me. If an employee gets a tip, that is not a problem. They must have done something right to be getting it.