Difficult to say! The problem is that we can't tell if a bot is moving the questions or a person. The only evidence of a bot, as Solar Wind suggests, is the speed with which the questions move around. However, I've been doing some experiments to see what happens so this is what I've observed ...
There was a question posted yesterday 'What is the Greenhouse Effect'. This question seemed to move back and forth between Global Warming and Abuse and Spam. Yahoo Joker claimed that if you tried to move the question to a different category, it returned to the Global Warming section. Obviously this raises the issue of why he wanted to move a question clearly about Global Warming to a different section! In any case, since I'd answered that question, I watched for a while yesterday to see how long it took to flip categories. In some cases it was 2 minutes. In other cases, it was 5 to 10 minutes. Why would a bot take different lengths of time?
At about 7 am GMT I had a look at that question. It was in the Abuse and Spam category. It remained there for an hour. This seems odd, since according to Yahoo Joker, it should have been moved by a bot back to Global Warming. So I moved it myself back to Global Warming. The question remained there for about 5 minutes, then returned to Abuse and Spam. I repeated the move, and it remained for about 2 minutes, before being returned to Abuse and Spam.
What I then tried was moving it, and clicking the icon to follow the question. The question hasn't, as far as I can tell, been moved since.
So ... I'm not sure a bot is actually moving the questions rather than a human being. What I am wondering is if level 7 users moving a question and/or then following that question pins it to a category?