I ran across this statement the other day
"He [Kurt Symanzik] used hand-written slides for an overhead projector (which were the industry standard at the time for technical presentations). However, he obviously wrote out his slides with lined paper underneath as a guide, using every line. So he ended up with over 25 lines of equations and text per page. His handwriting was typical German: undecipherable, at least to Americans, looking like endless up-down-up-down-up-down. The clincher, though, was when an equation on one page referred to an equation on another. He'd slap the second slide on top of the first, off-set the two by half a line and point to both."Source
And then there was the prof that I had for my partial differential equations class in grad school at Illinois. He would carry his own overhead projector into the class despite their already being one there. His projector was special - it had two handcranked rollers, one at the top of the projection glass and one at the bottom, with a continuous roll of transparency film . (You can see where this is going, huh?). He'd start out writing by hand the lecture, which wasn't a problem. The issues arose when he started referring back to earlier parts of the lecture, cranking the roll back and forth as needed, sometimes really getting wound up and going back to something that was written in a previous lecture. After a few minutes of this (questions only made the whole matter worse), everyone was hopelessly lost. Needless to say, I did not do well in the class. (A few well-placed drops of cyanoacrylate adhesive could have solved the problem, but there would have been no way that I would have not been ROFL clearly implicating myself.)
Sure, PowerPoint can be abused and badly mishandled, but whatever I've seen is but a misdemeanor compared to these overhead transparency capital offenses. By the way, check out the PowerPoint suggestions over at ChemBark. As he says, they'll make you a lot less annoying.