People and their sense of entitlement. Earn your fk'ing tip fool.
I'm the same way, if you give me good service I'm going to hook it up, I've waited tables before. Every one should do it once in their lives.
I went to a bar a few months ago. Had an awesome time, but the cracked out server ruined it. Outside smoking every other second, flirting with old men outside on the porch. Fucked up our tickets(we made it pretty simple, 3 couple, 3 tickets) and took forever to tab us out.
I left her a tip reflecting the service and a signature to let her know she was bad. Well I took a picture of it just in case she changed the tip. She did, she made the total $74. I called the owner told her we had a great time but she has some greasy servers.