Actually, I was under the impression that Political correctness was just using less offensive terms for certain occupations, medical conditions, minority status, religious beliefs etc. that are commonly looked down upon, as not to offend those persons.
It is based in respect, because even though you may be so superior and self righteous as to look down on "garbage men" or "retards" or "wetbacks", there is actually nothing wrong with them at all. They are not a "lesser" people as you were raised to believe, but valuable members of the community that serve a god given role and purpose that is 100% neccessary.
So instead, the Politically correct person calls them the "Sanitation Engineer", or "mentally challenged", or "Mexican American" because we realize that we are not superior. We realize that all religions are to respected, not just the one that worships a man on the cross. We realize that for a society to function that there need to be "sanitation engineers", fast food workers, and migrant workers, and that these people are just as valuable as white republican doctors and lawyers as our society would not function without any of them. We realize that people of diverse cultural backgrounds are all valuable, not just those that have a strong Aryan jaw and flaxen gold hair.
All in all, Political respectness is just the respect given to all people when you realize that we all have a role to play, a niche to fill in this world society.