I would like to suggest for CCleaner to add the ability in the applications section for the cleaner, the cleaning of uTorrent temp files, located in (Windows 7 x64 installation):
%AppData%\uTorrent
or
C:\Users\******\AppData\Roaming\uTorrent
If torrents aren't removed by right clicking the torrent, and then selecting "Remove And" --> "Delete .torrent" then that folder can become full of torrent files.
I don't know why it is said the "it is not safe to do so", since the provided link to the explanation is gone by now, but I guess it is because μTorrent uses some of these files.
FYI, there is a solution out there that "removes" only the TORRENT files that are not used by μTorrent: