I think Bundy defines the term split-personality. The major difference between him and other serial killers is that very often, I think you could see something wrong on the surface with them. John Wayne Gacy comes to mind. And a lot of times, they don't even care to put on some kind of public mask. Bundy's mask, however, was totally complete... to the point where you wonder if he wasn't split right down the middle, half-homicidal maniac, half-normal upstanding citizen. I don't really know, and I'm not trying to excuse it, but he fooled enough people that you have to wonder.
On the other hand, his indictment of pornography and slasher films is pure bullshit. I remember Kubrick saying something about high art and people thinking it's 'good for the soul'. He said something like, 'It depends on the soul.' Many high-ranking nazi officials loved high art and classical music, but it wasn't really chicken soup for their soul, now, was it? This was said in relation to Clockwork Orange. The interviewer asked about how Alex can love Beethoven, and yet he's a violent criminal. As if the two are mutually exclusive.
Likewise, the idea that slasher films and pornography are the cause of this behavior is utterly insane. Violence has been around a lot longer than the movies. Anyone like Bundy, who makes such claims linking his behavior to what he'd been watching at the time is looking for a scapegoat. He would have committed such crimes with or without pornography or slasher films. There have been scientific tests on violent criminals to show that they lack the normal empathic responses to human or animal suffering and that this causes a peculiarity where they KNOW they're supposed to feel something, but they just don't.
Having said that, I think that yes, it may make the impulse stronger, but they would have done it anyway. And knowing what he knows about his impulses, which 'normal' people don't have or at least do not act on, he has a CHOICE to stay away from it. Nobody sat Bundy down and forced him to watch porn. Lastly, if this were true, you would think there would have been a proliferation of serial killers and violent sexual criminals with the advent of the internet, yet things are as they've always been. I also suspect that serial killers have been around for quite a bit longer than the last 50 years. It was probably just a lot easier for them to keep it a secret before the advent of television, neighbors with a lot of time on their hands, and every small town in America having it's own police force. I think in other countries, it's still easier for them to go unnoticed, as was the case with the Austrian guy who had his daughter and the children he fathered with her locked in his basement for over 20 years.