It is happening a couple of times that some of my comments were deleted.

In one occasion, there was a discussion on some LaTeX edits that were made to a post of mine (Rudin assumes $(x^a)^b=x^{ab}$(for real $a$ and $b$) without proof?) which I admit was not completely relevant, but still helpful to me. The comments were deleted without any kind of warning or message.

Today, I was looking to a question of mine which was answered in the comments, and I was pretty sure I made two comments thanking the people who answered; again they were deleted without warning or notification.

Honestly I don't like that. I understand that maybe they were not completely on topic but we are still people so if someone helps me I thank him. And don't give me the "Every thank you message is more words to read and it's useless" explanation because this is taking to unreasonable extremes a very reasonable guideline.

At least send me a notification of the deletion! Does this happen often? It happened to me two-three times in the last 10 days!

• What purpose would the notification serve? – quid Jul 24 '15 at 15:28
• @quid To put the user in control. I don't like it when I don't control things. So if I think I have commented on an answer and I come back to it, I expect to find my comment. If it's not there I'll get confused for a while (did I comment or did I dream about that?) Maybe I'll post the comment again thinking I just forgot. And I believe the folks at ux.stackexchange.com would come up with more reasons – Ant Jul 24 '15 at 15:31
• I can sympathize with the aspect "confusion" and a desire for transparency. The point is though that for the most part comment deletions concern things that are not relevant anymore or never were really relevant. Notifications of that form to me seem mainly like wasting people's time and pointing users' noses into irrelevancies. "What?! Somebody found my playful remark from three weeks ago 'not constructive.' How dare they!" Not rarely in this context, ignorance is bliss. – quid Jul 24 '15 at 15:40
• Hello, this comment is irrelevant. Send me notifications of this comment's removal. Thanks. – PleaseHelp Jul 24 '15 at 21:16
• @AtulGangwar Irrelevant indeed – Ant Jul 24 '15 at 21:17

There was a flag on the comments saying the conversation had veered off topic. A moderator responded by removing the comments. We often do that in response to comment flags. More typically in response to a system flag due to the sheer number of comments. Less often somebody says something somebody else takes offence on and mutual flagging ensues.

It is a judgement call what exactly gets removed. I try to keep comments relevant to the question (or bits of lighthearted humor!), but sometimes they become collateral damage. In particular if the connectivity component (vertices = comments, edges = references/replies) of the comment contains something that should not stay there.

Other moderators follow their own scripts when handling comment flags.

In the present case the deleted comments do seem to have served their purpose. Nothing questionable in them (chit-chat on TeX and such). Do you remember something specific about them that you want undeleted?

• No nothing specific, I made my peace with that, but I'd like to know when my comments are deleted (and maybe why? Like "your comment was flagged for spam and hence deleted") . Maybe I should change the question to a feature request? – Ant Jul 24 '15 at 15:34

Your concern is, to an extent, legitimate. It's not nice to look for something in vain.

On the other hand, I've understood from moderators that there are entire oceans of comment flags (among others) daily which are completely legitimate, from users who read back on old answers (I'm commonly in this situation when perusing the Unanswered tab). We really don't want to bother people with the deletion of all their years-old honest remarks that triggered a subsequent edit to a post and hence served their purpose.

I am pretty sure that the moderators (try to) take into account factors like the age of the thread when gauging what to do -- we wouldn't want to delete a "thank you" without the recipient having a chance to read it, would we? On the other hand, if some comment flag is borderline now but would be completely fine in a week, I'd say that deletion is still warranted.

So while I see your point, I think that these cases are sufficiently marginal that they are worth the sacrifice compared to the resulting optimisation of the site as a whole.