Re: Zombies don't read old comics.
I seem to vaguely recall that yellow/fear was previously stated (or maybe implied?) as 'causes great fear' not 'feels great fear'. Bart's not scared, he's good at scaring people (yes, like you said, remember what he did to the Joker). *giggle*
Aha! http://asylums.insanejournal.com/scans_daily/775672.html#cutid1 <-- Most of the way down, there's a page with a bunch of yellow text boxes that have in them what seems to be the Sinestro Corp's version of the Green Lantern chant thing, and implies that theirs is to cause fear. They're saying Bart would make a good Sinestro, apparently, which I find unbearably amusing.