There are some cases in which a bug grows in an insane manner with just "spam" bugs (like bug 61098) or with comments that are just a result of an error on the user's part (like bug 569400 comment 47, although maybe Bugzilla should have detected this abnormal quotation too -- be sure to file that as a different bug). So, in a similar vein as bug 259452, there should be a way to hide these comments by default for every user of more than 1 user agrees on marking the comment as "noise".
s/"spam" bugs/"spam" comments/
Yeah, agreed. Once we have a system for tagging comments, we can set up a system for hiding comments with certain tags.
For me it would be good enough to collapse a comment permanently. Since comment is only collapsed, and everyone can expand it again, there is no need to have complex rules to decide if a comment should be hidden. Everyone should be able to collapse or expand a comment that he thinks is (or isn't) noise, permanently, for all users. Every user can expand to check if collapse was justified. The current collapse mechanism I consider useless, because it is not permanent, and not for all users.
The proposed solution in Comment 3 would be extremely useful.
this has been implemented as part of the work on bug 793963.