In other words, haterz gonna hate >.>
There’s always going to be at least one person who doesn’t like you, your panel, your presentation style, or just hates everything entirely. Most times you won’t know why or what you can do to alleviate this hate, you’ll just have to deal with it. It’s a natural part of life for people to hate things, in some cases just ‘cause, and you shouldn’t let that get to you. Even popular panels/panelists will have somebody somewhere who absolutely despises it, or at least doesn’t care for it all that much, so don’t expect to be the “special case.” The only thing that matters is that an overwhelming majority of the people who saw your panel(s) likes them. If it’s the reverse and a majority of people (or even half & half) either dislike you, your panel, or both, then it’s time to go back to the drawing board. This way, you can figure out what you’re doing wrong and how to improve it, which may involve asking some of the more approachable “haterz”. Otherwise, never let potential hate stop you from pursuing doing a panel on whatever, just use it as something to help you develop more of a hard-skin/backbone so stuff like this can just roll off your back. However, with every panel you should be constantly looking for ways to improve it; streamlining it, adding more graphics, less/more text, whatever, there’s usually always something you can use to improve your panel.
One way to seek out this “hate” is by going to the forums of the con, namely the feedback forum thread or any panel feedback thread, & seeing if anyone said anything about your panel. That way you can directly approach people who had problems with one aspect or another with your panel, find out what they didn’t like, & potentially use that to improve your panel for the future. Just because they’re hating doesn’t mean they aren’t somewhat justified in what they’re saying, because you can learn some invaluable things about your presentation, and yourself, that can help you improve for the better. Mind you, I’m not saying to do this so you can get in a flame war with whoever said something negative about your panel, but to proactively seek out the people who saw your panel to get feedback. However, the more “controlled burn” way of doing this is starting a forum thread asking for feedback for your panels & maybe putting in a line about not just listing problems but also suggesting solutions so you can take notes from that to make changes where need be. Of course, there’s always the risk of having to deal with “that guy” who just wants to be a d*uche to people & won’t really state anything that’s the least bit helpful, but just the fact that you could be catching the one piece of helpful advice makes it more or less helpful (not to mention you can usually delete/ignore/report comments to your own thread topic). Heck, in life people won’t always say things you like to hear, with panels it’s even worse especially when you look at the good, the bad, & the ugly of the fandom your panel is placating towards, so be prepared for it.
So, to wrap this up, people will always nitpick & find something wrong with your presentation to criticize, but that doesn’t mean you have to listen to these people & it’s just what happens & you shouldn’t let it bother you but use it to build on & improve for the better.