This story is so long its ridiculous but some ppl like details so here you go.
Obviously havent spent hours with them, but here was my experience: I met them both at the most recent awesomecon. First met them briefly in a line to get pix/autographs. Tim was concerned that they wouldnt have time to see everyone who had waited in line. He was very polite and has a cute manner of speech and said something like "please be mindful of the people behind you" because some fans were chatting with them way too long, and they wanted to chat but also accomodate everyone.
Took a pic with Tim again when there were just a few fans left. It was after the wave runner ride and apparently everyone just wandered away. I waited like 15-20 mins until they walked back up the dock to the sidewalk. Eric is very gregarious and was already mingling right away when he got back up the dock. Tim is reserved, has a serious (worried?) and thoughtful vibe to him, and he kind of just stood around alone while Eric chatted all over the place. I went up to him and asked for a pic and he said sure, put his arm around me, and we exchanged a few words about the jet ski ride "a little chilly" is what he said. I helped some younger fans get pix with them too because they were too shy and that also went well. When I asked for a pic with eric, he was obviously more outgoing, put his arm around me, (was a foot taller than me!), then just chatted about comic-con, etc. I think that Tim is shy and not comfortable in a random social situation. When he wasn't performing, he didn't draw any attention to himself and was quiet. He does not stay "on". I found them both to be very sweet during the whole event. (I'm female, early 30s, if that makes any diff, the other fans I took pix for were teenagers) Liked their vibe, they were "normal" and likeable.
I kind of consider anything that happens during a show to be part of the show, if its rude or not. I think he just sort of stays in character during and after the live shows and has a way different personality in regular life.
In related news, I met weird Al around that time period and he was so nice and self-effacing I couldnt believe it. He acted like HE was grateful to be meeting ME instead of vice versa. Met him at a Rifftrax event and those guys are also the absolute nicest,
on shy performers: I was extremely shy as a kid but I also spent most of my life prancing around onstage, singing and doing plays. It felt normal to be onstage, but then when I had to interact with people outside of that I felt so awkward and shy. ya know?
He bit me 
