Do you have a source for this? Every analysis of exit polls I have seen (for example: http://www.fairvote.org/plurality/perot.htm) shows that Perot split the votes fairly evenly.

Strangely, I can't find much either way. I thought there was a clear case for Bush over Clinton absent Perot, but I may well be wrong.

I also worded the original comment too strongly. Clearly, charisma is a big factor in modern elections, and one data point isn't enough to disprove anything in any case. Concluding that "it's charisma, stupid" does seem to rely on very small-number statistics, though.

While Bush senior might have won without Perot, I don't think it takes down the "charisma wins" argument, since I don't think it applies in elections where there's an incumbent running. The incumbent has a clear advantage, and is presumably already somewhat charismatic since he got elected the first time. While Clinton was certainly more charismatic than Bush, Bush's incumbent status should have been enough to overcome this and win.