The amount I give is dependent on the service. I am not proud to admit it but usually I am inclined to tip attractive person more. I think we all are if we are honest. Not a huge amount but it seems we are prone to like them more and it's human nature. Some people act like it's their God given right to get a tip. It's not really. While it is expected by social mores, there is no penalty for not tipping therefore it's not a right. All you will get is a loogee the next time you eat their if you tip poorly I would wager.
I tip 99.9% of the time. But if service is really bad. I 've stiffed them a few times. It was really bad with lipstick on the glass that I was given on to drink from, no check backs and general no service so I pulled a Mr. Pink on that one. A few times, especially if it's a kid working through college or the like, I have tipped the same amount as the meal. I am big guy and if I frown people actually cower. No one is going to complain if I don't tip but I have only done that maybe one time out of a thousand. Usually the servers fight over me as I tip well enough that they try to be my server the next time. I tip pizza delivery guys, bartenders and barbers too. Bartenders definitely are best bang for your buck on a tip. They serve you stronger drinks and will work you in when you need a drink if you tip early and tip as you are leaving.
While, I don't care for LeBron's vastly over rated game nor his penchant for choking when it matters, I could care less if he tips or not. It's none of my business, nor yours, to be honest.