As for things like "sexual perversion" - that's been around for as long as humanity has been around. They've found pornographic cave paintings. The only thing the internet has done has been to allow humans to share sexual content anonymously and easily. I'll bet my life that all the "twisted" stuff you see on the internet now was going on before, it was just a lot harder to stumble across.
As for people acting like jerks - again, the Internet is somewhat to blame. It hasn't made people nastier (again, Genghis Khan didn't have himself no dial-up, and look how he turned out! Vlad the Impaler didn't have DSL and Hitler never went to 4Chan, and look how evil they were!). But the internet is responsible for lowering the social taboos. It encourages people to vent their innermost emotions and prejudices and meanness, because there are no consequences and because it's so easy to do it. Anyone who has grown up with a keyboard can write an offensive, demeaning post within literally seconds, and the very nature of the internet encourages them to do so - "Don't reflect! Don't pause! Don't screen your own emotions and calm down! Post whatever, whenever, however. No consequences, no hassle, no trouble! Just burble whatever you feel like without consideration! And of course, as we all know, the FASTEST COMMENT WINS!"
Again, without the internet, people have to write or send things by hand. You have to take the time to craft a response, take the effort to print out or write out the message and pay money to send it. Usually (but not always), people would catch stupid thoughts before they made it to the envelop. Also, the process and cost associated with a letter meant that they wouldn't just write nonsense - they would have to feel motivated and invested in a subject enough to bother sending a letter. Also, without the internet, you'd have to talk to others. This meant that you'd have to look your opponent in the eye and hear whatever they had to say, and if you came across as looking like an idiot, it would affect your real-life reputation. On the internet, Rep doesn't exist for most of us! Unless you are famous, your identity is as fluid and meaningless as you want to be. I know of several people who have "trolling" accounts on popular forums. Whenever they got banned, they just made a new account.
The Internet has not made us any nastier, more prejudiced or sexually "perverted" (I don't like to use that term except when referring to rapists or pedophiles or those who pratice bestiality or incest. Those are the only ones who are really sick. I might not understand the "furry" crowd, but as long as what they do is consensual, I've got no problem with it. Provided it is behind closed doors where I don't have to see it). It has just removed our ability to think and reflect on what we say and write.