In the case where someone answers a question, and the asker or someone else thanks the answerer for the answer in a comment, is site etiquette (A) to respond with a "you're welcome" comment, since that's what normal polite conventions of conversation would require, or (B) not respond with such a comment, since it has no content and clutters up the site?
As a Stack Exchange user, I personally will often post a second comment saying "You're welcome" or such, and then often flag the comments as "chatty" or "obsolete". Doing so will alert Moderators and other high reputation users that both comments can be deleted while also leaving an inbox notification for the original user.
Each site treats comments like this slightly differently. On Cognitive Science, as a Pro Tem Moderator, I have received the impression from the flags we receive that most of our users prefer comments like this removed. I also understand that people like to express gratitude, and I personally have no problem with users thanking each other and my cleaning these comments up later.
This same question was asked on Meta Stack Overflow and the highest voted answer basically confirms my feelings. Also, to quote Aaron Bertrand's answer:
I sometimes delete "you're welcome, glad it helped" comments after I know they've been seen, just as I do if I point out an error and it gets fixed. But if the answer is accepted and the question has been answered, I don't think there is much harm at all in those comments staying there. They're not taking away from anything except a few pixels of vertical scrolling for future readers.
This is very much how I feel also.
Note that I would very much like other Cog Sci users' answers to this question so we can as a community establish a policy for how this should be handled as I don't feel I have been given clear direction from the community on this yet.
My view (for what little it is worth) is that leave it there for a short while and then flag to delete the comment - this way, there is a good chance that the person doing the thanking will see the response.
Alternatively, just state in the guidelines that the 'you're welcome' is implied and is not needed to be posted. We are all pretty polite and don't usually bite - that comes across very clearly (and is one aspect that attracted me to the site).
I prefer the solution of not posting "You're welcome".
As Damien wrote, its implied.
The proposed solution of posting and then flagging creates unnecessary work for our community moderators. I'd rather have them use their time to improve the actual content of the site, rather than clean up our polite talk.