I was looking through my server logs tonight and noticed activity on my /wiki branch. Although not private, it's essentially a seldom-used service to myself and a few others. That it was experiencing high traffic was a bad sign.
So when I checked, yes, of course it's a bad sign. Just like with every other publicly-accessible web service, there is a problem with spam bots. The interesting thing was that they seemed content to just pollute the index page, but none of the subsidiary pages. This means less clean-up work for me and easier for me to protect that single page.
The more interesting thing is that a secret war was going on among various spambots. For months every day bots logged in and wiped out each others' changes, replacing one's spamlinks with their own.
It sort of reminded me of the US Army's secret fights to eliminate salafists in North Africa or Al Quaeda in Djibouti.