What's the worst site you can think of when it comes to other peoples' comments on videos, articles, exc? Yahoo, to me, is the absolute worst, even more so than YouTube.
I can't say I've ever checked out people's comments on yahoo. But it's hard for me to imagine they can be worse than many of the comments that I've seen on youtube. Some of the comments on youtube just make my skin crawl.
I think you can find offensive comments pretty much anywhere on the internet though. I frequent a lot of sports web sites and I've seen hurtful, offensive and racist comments on cbs sports.com and also ESPN.com. The internet is a wonderful thing, but it can also be a horrible thing when you have truly gutless people hiding behind their keyboards in anonymity and typing whatever the hell they feel like saying without any repercussions.
Twitter is another "dangerous" tool when put in the wrong hands. You have athletes and celebrities and even regular people just spouting off whatever they want off the top of their heads without thinking about what they're saying. Then if they say something offensive, they come back and say "Oh that wasn't what I meant" or "Oh that was taken out of context".