You don’t have to be LOOKING for porn to hit these things. I’ve hit these traps doing completely innocuous things. WAREZ sites are famous for doing this, and you can easily wind up on a WAREZ site without intending to, because they’ll show up in searches for legitimate things.
I’m a licensed owner of Cakewalk, a MIDI sequencing program. It’s also one of the commonly hacked programs. A while ago I had some technical problems with Cakewalk, and did a web search to find some cakewalk sites that might have some info. Probably half the sites that showed up when I searched for ‘cakewalk’ were WAREZ sites, and you often can’t tell by the snippet of information you get from the search engine. So you click the site, wind up in warez hell, and when you leave you get re-directed to a porn site you don’t want to be on (warez sites seem to often be affiliated with porn sites). Try to close the window, and you have 20 popups of porn images all over your screen. Whee.
The best part is trying to explain to your wife why your browser history shows that you were on 20 porn sites last night. Especially if they have lovely names like “TEENSEX.COM”. And yes, I know I can delete the history or any item, but then I either have to go through the damn thing one at a time deleting the offending sites (and deceiving my wife in some small way), or delete the whole history and lose a lot of links I may want.
My brother was visiting at Christmas, and I let his son use my computer to play around on the internet. Well, all hell broke loose when my brother walked in on his son and saw a whole screen full of porn sites. The boy swore up and down that he didn’t do anything, and didn’t intend to go to any of them. So my brother called me in, and I saw the ‘pattern’ of popup windows which were self-spawning. So I traced back through the history to see what the kid was doing, and sure enough he didn’t mean it. He was on a very innocuous teen chat site used by the kids in his school, and followed a link to a site called “TeenFun”. This trapped him into popup hell, and he didn’t know enough about the Internet to figure out how to make it all stop. He kept trying to close windows and he’d just get more. Then Dad walked in. The kid was very upset about the whole thing, as was his Dad.
At the request of his Dad, I went through the history and brought up every site the kid had gone through, and not one of them had any indication of sexual content. The poor kid just had no way of knowing. And suddenly he’s being bombarded with images of Anal, oral, animal, and every other kind of sex.