In all honesty if I got a comment from an individual who later ended up regretting it, I would prefer they hide their own comments. It saves me the trouble of having to do it. But yes, I would prefer they don't post at all. Then again, if you don't know who posted it, you cannot block them either.

I think the party(ies) has something to hide.

If you got other comments at about the same time, then it might have been one of those people hiding a mistake and starting over with a new comment.

Now that we can edit comments, this shouldn't happen too often. I just edited this one on purpose, just to see how it worked - my very first comment edit on here.

I have the same problem too, and also users favorites something on my submissions and than un-favorites for no reason, it will never stop, and they're comments removed, ether if it's a positive comment or negative comment.