I've read that some people have had problems with icons not reverting or changing when using Iconpackager, which prompts them to use Icon Cache - Rebuild
Before I used the tutorial I had a problem with only half of my folder in a particular library not changing. I'm changing the color of the live folders and half were the new color and the others were stuck with a color I did not like. They would not change colors or even revert to the default icon so I was about to use the tutorial and the I accidentally moved the contents of one of the folders (color I hated) and miraculously the host folder changed to match the other folders. I did the same with the other 6 or 7 folders and viola, all folders match. I'm not sure how to explain this, but I am happy it worked so I thought perhaps it may help someone with a similar situation.