Of course this dislike is not without basis. A couple of graphic designers have been running the Ban Comic Sans campaign for some time now, featuring "propaganda" such as stickers, shirts, and web graphics. Their tongue-in-cheek advocacy is to stop all use of Comic Sans not because it's a bad font per se* but because it has become the default font for anything "whimsical" or "kiddie." According to the Combs:
While we recognize that the font may be appropriate in a few instances, our position is that the only effective means of ending this epidemic of abuse is to completely ban Comic Sans.
They're right, or course. It works, as originally intended, inside comicbook balloons at 12pts or smaller. Using it to set headlines on huge tarpaulin banners on the other hand just smacks of abuse.
* But there are a lot of better ones like Anime Ace, available at the bancomicsans site