Generic Folder Icon problem in Mavericks

This seems long overdue but are do you still have problems recustomizing your genericfoldericons? I experienced something very similar to what you described. Here are some of my suggestions (quick fixes):

1. Download candybar - its a utility that does the same thing with changing icons and has a nice GUI.

Once downloaded, change the genericfoldericons by reapplying your custom icon. Thereafter, it prompts you to log out to preserve the changes. Log out, restart your computer and the genericfolder should be updated to reflect your custom icon.

Although this worked for me and if you eery about candybar, you could simply try logging out, logging on, then restarting your os.

2. Try Relaunching the Finder. Holding the "options key" right click the Finder icon on Dock. A popup should appear. Click "Relaunch" and afterwards, restart your OS.

3. I have a feeling it has something to do with .DStore or MetaData files that were created in the event you copied/pasted your icon. I confirmed this was not the case with my mac as I navigated via terminal and couldn't find if after executing the terminal command: ls -laxo in the directory /System/Library/CoreServices/CoreTypes.bundle/Contents/Resources. Check if you have it and if you do, remove such files but I do not recommend this as (if you don't have experience with bash/terminal) can permanently delete system files.