Most applications seem to do a decent job of cleaning up old log files, with the exception being the launcher (it doesn’t seem to do any).
Also, if a machine has log files on it from a slave that no longer exists (or, say, from the parent image in a drive cloning situation), those logs are basically orphaned.
In the Application Data section of the Repository Options, there should be a value for deleting old launcher logs after a certain period. Can you verify what this is set to, and that there are logs on your machines older than this? As for the foreign logs issue, that sounds like just an oversight on our part and I’ll see if we can get that fixed for a future build.