The reason I've been thinking about comment flags is because in August 2016, we implemented a new auto-flag for moderators to point out users who consistently have comments flagged as rude or not-constructive. In looking at how accurate these auto-flags are, I've come to the realization that they stink. It's not because the auto-flag is bad. It's because users are flagging comments with the wrong reasons, moderators are told to process comment flags quickly, and spend very little time thinking about comment flags. As a result, we have poor comment flaggers, with no correction of the poor flagging, which then leads to noisy auto-flags being thrown at the moderators to handle.
I fully agree with minimizing or consolidating the flagging options, as suggested in the question. However, I'm concerned about the category 'Noisy'. Using 'noisy' to include things that have little value, aren't needed, or are unnecessary, sounds ok, but I'm unsure how many people will understand that definition of the word. I went in search of another word or phrase for it and got a lot of really good suggestions. I also like some of the suggestions by Robert, but I think they are getting too far into the weeds. The comment flag categories, in my opinion, should be easily recognizable to minimize any confusion.
Keep this category as it falls in line with the Be Nice policy. When handling these moderators will be able to [Delete] or [Dismiss] from the flag queue and if necessary, they'd message a user with a suspension if required.