I must admit, I do tend to look a bit odd. I don't have green spiky hair or lots of piercings but I'm not one for pretty dresses. At 24 I still get followed around in shops. The classic was a few years back I was looking at pick and mix sweeties. They're on a round counter in the shop, near the checkouts and I noticed a security guard was following me, in case I decided to steal 10p worth of sweets, presumably. I walked right round the counter, making sure I got all the best chocolates. Guard followed me. I walked round again, just to test. Again he follows. by this point the checkout staff are watching / giggling. I walked round the stand six times before he realised. Silly security guard.
I'm not sure if you have the same thing in the US, but in some department stores there is a high pitched buzzing that adults can't hear but it bugs the life out of kids / teenagers. I have very good hearing so I can still hear it and I have to say it's annoying. These shops don't seem to understand that teenagers can be customers too. After all, I know a seventeen year old who earns more than I ever will and likes being accosted with new perfumes.
and in my hometown there was The Bench. Despite being a very big town, bigger than a lot of cities, there is nothing for teenagers to do. As such, at the weekends a lot of alternative/Goth/grungy teenagers would meet at the bench. The council took away the bench, saying the teenagers looked scruffy. What they had failed to consider was that this was also the bench by the post office, where the elderly have a sit after they collect their pension. So the result was elderly people falling over, oh. And the teenagers who used to meet at the bench now hang out outside the council house.