I thought you might be suggesting that no-one is actually a utilitarian, although they might believe they are.
When I said I had never met a utilitarian, I meant, literally, that I have never even met someone who claimed to be a utilitarian. When I said that I am sure that there are sincere utilitarians who try their best to use the doctrine to guide their actions, I meant exactly that.
As far as I am concerned, someone who tries to be a utilitarian really is a utilitarian.
It seems to me that usually, when someone says "ethics" on lesswrong, ey usually means something along the lines of decision theory. When an average person says "ethics", ey is usually referring to a system of intuitions and social pressures designed to influence the behavior of members of a group. I think that a lot of the disagreement regarding ethics (i.e. consequentialism vs deontology) is rooted in a failure to properly distinguish between decision theory and what society pressures people to do. Most lesswrong users probably understand the distinction fairly clearly, but we only ever talk about decision theory. Why don't we talk about the social meaning of ethics?