That's because it's always disappointing when someone doesn't look like Harrison Ford.

Of course people associate avs with those who use them, just like sigs, font size/colour, frequent misspellings, and any other gimmicks (Hi The Devil ^_^!) that people use to get other's attention. It's the same anywhere - there are plenty of people I work with who wear pretty much the same colour palette week-to-week, and isn't it always scandalous when someone chooses to break out of the mould?