Every now and then I run across a comment that is far too stupid, off-topic, or poorly written to leave in existence. I delete it. I take the stupid and just wipe it away. A clean slate, minus the deleted comment message. But no one knows what it said. I make no record of it and never mention it.
They're all my own. I post a comment and look at it a second later and go "wow, that's stupid" and away it goes.
Is this much different than making an ignorant claim and then editing it and deleting the comments that remain as evidence? The reason is the same: to hide a brief moment of stupid. Does it really matter all that much that they're my comments and not those of others? Yes.
The speed of the second thought and deletion is such that no one actually sees it. This is significant. It's one thing to say something stupid that everyone has seen and then to try to hide it, another to say something stupid and hide it before anyone sees it. The method is varies, but in effect isn't all that different from my draft folder filled with posts that I intended to post but realized were crap? There's nothing wrong with changing what you say to make a better impression; changing what you said is a different story.
The inconsistency is another difference. I don't delete everything that I find is stupid. If it's been up for long enough to be seen, it stays up unless the blog owner deletes it. The same with my posts here: I sometimes post something and then retract it a few seconds later, sometimes editing it to post on a different day; but my posts which have been up for a while stay up. Go searching my archives, I'm sure you can find something stupid without much effort.
Sometimes I do edit my posts, usually to add in something I missed. I put a little  marker in and put new stuff at the end. Sometimes I rephrase things slightly to assist comprehension. But I do not remove content after it has been added, at least not without mentioning it. Even my stupid comments leave a little marker that effectively says "the commenter didn't like this enough to leave it up."
But in the end, aren't we all running our own little version of 1984 as our very minds rearrange our memories?
Yesterday's post has a deleted comment. You can't see it because I deleted it so hard it ceased to exist at all. Gold spam gets no mercy.