Why do some people wear really horrible looking clothes?

One mans tracksuit is another mans tux, I guess...

Maybe they have bad taste...

To scare bad spirits.

Sounds subjective to me.

I must agree with Rokasu, and that's a rather rude statement as well. Many people choose to wear what they're comfortable in, can not afford anything else, wear certain for religious or cultural reasons, wear a uniform, the list goes on and on.

It might be all they have, or they just want to be comfortable.