I do. But its not as much their clothes, tattooes, piercings etc. as it is their body language or facial language. It takes me just a few minutes with a person before I have it down to how they are. And in 99% of my judgements, I have come out as right.
I won't thoroughly blame those who judge people for the way they dress. Chances are huge, that that woman over there in the jogging pants, moonboots, thin jacket, dirty, unwashed hair and with a cigarette in her mouth, are a social client, alcoholic and possibly druggie.
The girl with the tight top, skimpy skirt, blonde hair and oompa loompa tan is most possibly a bitch and simultaneously emotional wreck cause she only falls for the bad guys.
Fully dressed up gangster with bling everywhere standing at a street corner with his homies? Douchebag and possibly criminal.
Of course there are exceptions and thats good. But those exceptions suffer because the rest of us are quick to judge. I am not really sure how we can 'solve' this. One way is to be a bit more open and non-judgemental. But you would all agree with me that if you meet the gangster gang alone at the middle of the night at the street corner, you will turn around and walk the other way. Chances they'll mug you are higher than if it was a gang of average looking people.