Hmmm, well it's not just the smilies, it's also the default paper image that shows up for posts. I need to edit the actual image path for the icons.
If you can, go here,
http://www.infiniteguitar.com/forum/index.php. And at the bottom select the IGTest2 skin. I'm working on editing the images right now. But you can see that the thread icons are still pulling from the darker skin's image path.