> 7. Bad designers. Oh yea, there's -a few- of us out there
  > that just picked up GIMP yesterday and think a
  > 600 x 600px favicon should be fine. Even designers
  > capable of really good work may not understand why
  > a 2400x1600 image cannot be used thumbnail-size on
  > the page. This is sad, but I've seen it.

There are a lot of designers that think that there is zero difference between print design and web design. The only difference being sending the finalized design to the printer or the programmers. (I.e. I design in my little corner over here, and poop out my design to you code monkeys that are little more than the automatons that will construct my vision) This may not apply to all or even a majority, but there are good numbers of them out there.