I would recommend listing several directories to be backed up instead of trying to excluded one or delete it. According to the man page for tar you can simply list multiple directories, so your tar line would now look something like:
I haven't tested the command so I'm not positive that's right, but it should be. definitely seems easier to do that then go back and delete unnecessary files, especially if it's very much data.
On a side note, I'm not positive, but I think that if you backed up your entire home directory .snapshot would not be included because it's a specially hidden directory, and doesn't show up on any directory lists. Generally the way programs behave is to get a directory list and then specifically access those directories and files. So if the directory can't be seen, then it stands that it also wouldn't be backed up. Note that this would not be true for standard hidden files and directories, just the .snapshot directory because of the way DH has configured it.
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