I just ducked into my house (from work, shhh) and almost half of my SDBs have disappeared, with all their contents. There are only three keys to my house, two held by very trusted friends and one by my wife, who never logs in at all and wouldn't know what to do with an SDB if she saw one.
So it doesn't seem as though it can be theft (inside locked house) — am I missing some other explanation for vanishing treasures?
Later: They just reappeared. I don't need to go out for a whisky after all.