Bad places, good places

Not the safest place on Earth if you are a bug. Image is CC BY NC SA Hannes E.

Are there bad places on the Web?
And I do not mean one of those web sites that look like they are straight out of 1992, nor places which offend a coder's sense of beauty or the browsers' by using malformed XHTML or whatnot. I mean the bad places for real, those places you might get uneasy, upset, or scared visiting.
My gut answer is yes, there are plenty. As much as we have come to terms with the idea that a phone call can be as threatening as bumping into the wrong guys on the street, I think it is entirely plausible that we have such things. But then, what exactly makes a bad place bad in information space? Is it even entirely possible to think of bad places on the Web as places? And if it is, how?