I've seen a good bit of chatter about flagging comments more and more as part of the effort for some user to get the Deputy badge before the Community user. It was suggested that flagging comments was one of the main source of flags for users with higher rep since most of their actions on questions become close votes rather than flags. This suggests to me that I should be flagging comments more than I am now (read: almost never).
The mouseover indicates that a flag should be used when something is "noise, offensive, or spam". Offensive and spam are easy enough to determine. What about noise? What constitutes noise for the purposes of a comment?
There was a closed question where I decided to flag a few comments that fit my personal definition of 'noise'. The next day, I had a higher flag weight than before. Some might say they have a purpose because they are "funny", though, which makes me wonder if "non-informative comments made purely for the sake of 'lulz' qualify as noise in comments.
I'd appreciate input from other people on what qualifies as noise from a site policy perspective.