[CJefferson]

I have a friend who got their paper retracted, because it turns out they had made a big mistake in implementing an algorithm -- so big that after fixing it, the results entirely disappeared.

In that case, the retraction isn't didn't really get any publicity, and I'm actually proud of them for doing it, as many people wouldn't bother.

However, in practice I would say the majority of retractions are for wrongdoing on the part of the authors.

I wish, particularly in the case of the modern internet, that it was easier for authors to attach extras to old papers -- I have old papers where I would like to say "there is a typo in Table 2.3", and most journals have basically no way of doing this. I'm not retracting the paper over that of course! This is one advantage of arXiv, you can upload small fixes.