On Mavericks I have been having quite a few issues with icons disappearing, particular non-standard ones (e.g. Dropbox folder). Restarting seemed to be the only way to fix it, until it happens again.
This issue seems to be overlapping with a com.apple.IconServicesAgent bug that I, and many others, am having - though not sure if they have TotalFinder installed or not. Basically it starts maxing out the CPU due to a permissions issue on its cache folder.
After uninstalling TotalFinder during one of these icon disappearances (everything in my home folder) all my icons returned.
Anyone else having these issues? Definitely feels like Mavericks doesn’t agree with TotalFinder.