On top of the list of the most hated fonts would have to be comic sans. Although Comic Sans is constantly put down upon it has enough merit for its name to be bestowed upon one of the printers in the general lab, so even if you did not want to speak of comic sans...it is probably mentioned every day at Tyler because of that.
Here, a man named Mykl Roventine passionately presents his distaste for comic sans:
This video gives you the background of comic sans and why not to use it. I think it is important to understand what is bad about typography in order to know all the good stuff too.
P.S. Comic sans did not go down without a fight.