1.  If a comment is deleted early, and doesn't show up - it's likely through the peer-review system.

2.  Comments deleted through the peer-review system don't get the <deleted> indication.  That only happens if it made it through peer-review, but got deleted by a moderator after someone flagged it.

3. If a comment is flagged then deleted, it does not show up as <deleted> unless another Globe reader had already replied to it.  If no reply, it just disappears.

Those are my observations and conclusions, anyway.