I always try to leave a cash tip with the server personally even when using a card to ensure THEY get the $$. That way if they keep it, great. They earned it. But if they want to pool it, that's on them. I leave a good tip for good service. Usually 22-25% on average for decent service. If they really suck, I leave them a sucky tip like $1 or something. For effect. It's a non-verbal message. A minor issue now and again I overlook, but sucky service? You know it when you get it. They can get mad all they want, but I'm not going to be held hostage for tipping well for bad service. We went to a local restaurant a few weeks ago and the service was horrid. I had to flag down the server 3 times just to get my tea refilled. And when they brought out the food...it wasn't what we ordered. Oh, I screwed that up. Well, ok, so they had to re-do the order. What's worse, we were not offered any comps for any of it. At the end of it, I paid with my card, left $0 tip on it, and reached into my pocket and I only had 37 cents in my pocket. There's your tip. Maybe some pocket lint to go with it as well. Don't spend it all in one place.
As far as rewards cards- recall ALL free sh*t is good. But all good sh*t isn't free.