Quite a few times. Recently as our waiter appeared like a clueless halfwit barely able to breathe on his own without reminding so we left before I inevitably had to cause a scene. Then a few times at local restaurants. Eight waiters in the place, we the only clients and it took us 15min to get a waiter to come over. Ordered, ate, got up and left. Don't think they even noticed.
I generally stick to 1-2 restaurants I know are up to scratch and don't bother going elsewhere.