Wow, this is sort of a huge relief for me to hear. I've done the whole waitressing thing before, and I was completely horrible at it when it came to timing everything properly, and tending to peoples needs. When it came to the Fe aspect of it I was alright (though shyness and introversion didn't really help) but as a Ni ego type I was constantly stuck in my own little world, and no matter how hard I'd try I couldn't focus on my tables needs. It was actually really frustrating to me that I couldn't deal with these people the way they wanted to be dealt with, and I'd always feel bad about myself, especially when comparing myself to my ISFp friend who was a pro at it. I couldest relate to so many people at once, and like Mimosa Pudica I also couldn't handle the sexual remarks which actually really upset me.
It makes me feel better to know that there was a reason why I sucked.

Strangely, I was actually talking to my therapist about this yesterday (this particular therapist is really into MBTI) and he said that waitressing is probably the worst thing an INFp can possibly do. He also said that INFP's make good bartenders because of their ability to relate to people on a one on one level.