Imagecache not showing images

Oh my god that was SOOOOOOOO annoying. We spent a simply silly amount of time trying to figure out why imagecache images would not display at all.

Resolution

Even though Agaric Design's site is now on Drupal 5, we hadn't changed the .htaccess file in the Drupal files directory since it was a tender young 4.7.

And therein lay the problem.

To quote from the imagecache modules page itself (a moral of this story is to always go there first-- in this case the answer was right on the front page before we could even look in the issue queue)

Drupal 4.7.3 generated a .htaccess file in the public files folder. If you are running Drupal 4.7.3
the following lines in that .htaccess file need to be changed.

Options None -> Options FollowSymlinks
RewriteEngine Off -> #RewriteEngine Off.