Ad hominem: Typically this term refers to a rhetorical strategy where the speaker attacks the character, motive, or some other attribute of the person making an argument rather than attacking the substance of the argument itself.
"retarded" = implying anyone that likes it is, well, retarded.
"shill" = anyone that likes this is ... an accomplice of a confidence trickster or swindler who poses as a genuine customer to entice or encourage others.
I debate people on many subjects, but when they start using logical fallacies (especially ad hominem) I move on.