Mine dropped to one for excessive following. However, don't just assume that people are following others just to try to game the system. In my case, I was under the impression that it was supportive to follow people and network. It was lack of knowledge rather than anything else. I didn't follow anyone thinking they would follow me back.
That might also be the case with this person. I'm sure there are people who do things like click on their own ads, but it is probably more likely that they don't realize they are doing anything wrong until their score tanks.
People on the forums were so helpful and my hubscore has climbed steadily since this happened. It's now in the 50s, which isn't a great score, but compared to the one I knocked it down to it isn't so bad.
A friend of mine told me not to worry so much about hubscore. Worry about traffic. I'm still too new to know for sure, but learning. I had my hubpages for 2 years before publishing a hub, so I have a lot of catching up to do.