The fan that describes a band's music to be shitty, but gives little to no reason why he/she thinks the band's music is shitty. Often they don't even offer a comparison to a band that is similar in "style" that they believe creates better music, or any band at all. Discussions on such a comparison can help to illustrate why they feel the way they do.
These comparisons can help us in an attempt to winnow what is absolute from what is personal preference... or at least we can try lol.