"...When I get bad service, they are lucky if they get anything..."

I used to just add the tip onto the bill when I payed by credit card, but recently had it explained to me that if I do that the employee has to pay taxes on the money, if I leave cash they may not. So now even that depends on the quality of the service. If I have lousy service and am leaving cash I leave a nickle. Leave nothing and they will just think that you are cheap. But for really lousy service I write "no tip due to poor service" on the tip line of the bill. I figure that someone up the chain will read that, and hopefully do something about it...