Non PC terms

There's a slew of words that can have offensive connotations and it's hard to know which ones to be concerned about. Especially as there are words which are innocent in one culture but not another (the term 'Oriental' to describe someone springs to mind, difficult for Brits to grasp as 'Asian' means 'West Asian' for most Brits). I'm bringing this up as I'm aware that 'retarded' is widely regarded as a demeaning term of abuse. It features in this as yet unpublished anonymous post: But there are already a few instances around JustBento. I guess I'm uncomfortable with it in the same way I'm uncomfortable when young people sneer "that's so Gay". I don't personally find the term offensive, I just tend to think rather less of whoever wields it (normally teens or people barely out of their teen years). I'm aware that this word is common currency for many so don't want to create a fuss. Any thoughts or guidelines?