A stereotype doesn't become a stereotype unless a significant portion of the population conforms to it....therefore, stereotypes are a good general indicator of who/what you are dealing with.
That said, I profile many people I encounter. I'm not one to fall for certain obvious (read:ethnic) stereotypes, but certainly culture and manner are clues to what I am dealing with.
Example: I'm walking down the street near nightfall. Walking towards me is a black man. T-shirt, jeans, sneakers. I'm not going to have that "Instinctual" fear of this guy, no matter the skin colour. Now, if I'm walking down the street and a black man walks towards me with pants half-way down his thighs, baggy Fubu shirt, a doo-rag on his head and gold tootheses....I'm gonna watch out. Not that he's GOING to rob me, it's just that he's far more LIKELY to rob me.