I can't speak for all "liberals," but I find the debate about racial profiling - rather, the non-stop whining on the Right that liberals would have complained about racial profiling had they tried to follow up and investigate Arab men in flight schools - really, really dishonest.
There is a difference between picking a man out of an airport line because he is Semitic looking and picking him out of an airport line because he carries a Saudi passport.
There is a difference between investigating people because they are brown and investigating them because of their country of origin.
I didn't have much of problem with Ashcroft investigating every single person Arab in this country because it was racial profiling (though to the extent the he investigated American Citizens of Arab descent rather than simply Arab residents, I would have), I had a problem with it because it was a counterproductive waste of resources which would do nothing but create resentment in the Arab-American community at a time when that was probably a bad idea.