Another interesting topic to think about. Ya know...I live out here in Vegas and it's just normal to tip. I usually do not even think twice about it. For restaurants, you really have to do a sh*tty job to make me even think about altering the tip. But I still tip. I do not have really many bad experiences. If service is slow I do take notice how busy a place is and if they are understaffed. Which is typically the case and if that is the case I NEVER let that alter the tip.

One time with my two children we were at a restaurant and they were busy. And our poor server was getting killed. It was slow but we still had a good time. When we got the bill I could tell he was apologetic. So I gave him a nice tip and thanked him for taking care of us. He looked SHOCKED. But I think it goes back to the "Kindness Contagion" piece you wrote. Perhaps this set a series of positive things to come from it. And I still had great time with my kids anyway.