I don't think we use the term Kettle in a derogatory manner, it's really just shorthand. Someone may remark that a Kettle who held a boarding pass for 38C thought 3B looked really comfortable so he sat there. The descriptor Kettle just tells us it's a person who doesn't fly often.

I think we are harder on fellow elites than we are on Delta or Kettles. The DYKWIA thread on this forum is pure gold. And I think it serves a purpose in that we might sometimes recognize our own transgressions in those shameful tales, and correct our own behavior.