retarded defense
not worthy of a response
you may be a nerd, but you ain't too bright
Personally, I think this "standard" politically correct defense is ok on a purely ethical level, but not on a "practical" level.
Stereotypes are useful heuristics for survival and navigation in a complex world. Of course I would not count my money while walking the streets in a poor black neighborhood. Hence, racism as a pure survival mechanism may be useful and unavoidable- as one of many useful stereotypes.
NN