People have messed with things and found bugs (so far always reported more-or-less ethically), and lots of scanners go across the Internet daily, but I've never seen a deliberate take-down effort. (Kind of wondering whether I'm calling that upon myself now, but so be it. Let's see what happens.)
This fear of having to react to a DoS attack by knocking on big brother's door and thus preemptively knocking, it's so anti self hosting mentality, but is also pervasive throughout the self hosting community, I really don't understand it.