What specific accounts have you heard? Did he spit on a fan? I think it would be nice to hear exactly what it is that has caused you to believe he acts poorly at these cons, despite video proof up above and two people posting here that they've met him and had positive experiences.
For the sake of being fair, I'll post some encounters I've had. I've met him several times since about 2006. In each event, he was more than happy to sign all my items and take photos with me. One time I saw him he had just gotten new tattoos and they were still wrapped up. I commented on how they looked great under the plastic wrap and he said thanks. Another time he signed a variety of posters for me. He didn't charge me to sign about five posters! I bought a photo from him after that point, but it didn't begin to make up for it. Last October he began charging to sign your stuff, but I got a few posters signed anyway and he was pleasant throughout.
Also, as far as I'm concerned, "not seeming interested in fans" does not make him a ******. Many people who attend these shows are in fact boring and they have no social awareness of how they should be conducting themselves. I've seen it myself way too many times. These guests aren't there to boost your self esteem and make you feel special.
Some guests are openly warm and WANT to spend 10 minutes talking to each person. That boils down to a personality thing, because remember your cash is only good for an autograph and a photo--not a tap dance performance.