The comment that a band is "good at what it does" is a polite attempt to acknowledge the talents of a group outside of one's wheelhouse. But the phrase tends to come off as a dismissive, backhanded compliment, the type of statement a person makes to avoid actually forming an opinion. The underlying element of snark comes from the dynamic between good and cool. Any musician, given enough practice, can be "good"; this is a prerequisite to get the most basic gig. Fewer musicians have reached the vague pinnacle of "cool."
Cool, of course, is subjective. I am not referring to the cool that cultural anthropologists love to dissect, the one of Miles Davis, Jack Kerouac and anybody who non-functionally wears sunglasses. I mean cool as a catchall for an individual's personal tastes. If you like Taylor Swift's music, you think it is cool. You may also think it is good, but as soon as one steps beyond analysis and into preference, this becomes a matter of coolness. Therefore, "good at what it does" easily translates to "not cool."
Good is respectable and can take years to achieve, but it is a simplistic accomplishment. It is a goal reached through the sport-like aspects of music rather than the artistic. I increasingly care less about how good a piece of music is and more about its coolness. This is in some way my rebellion against attitudes imposed on me over the years: the music-education mentality that solid musicianship outranks all other priorities and the music press mentality that certain artists and albums are infallible. It took strange courage to admit I don't like listening to Grant Green or U2, that I don't think either are cool. But hey, they're good at what they do.
While I am surprised when people see no distinction between good and cool, I fully understand the mental block toward music that is cool but not good. I get why people hate the White Stripes or Pavement based on unconventional or downright bad musicianship. I frequently find myself trying to explain why Neil Young is a great guitar player because he's an awful guitar player, or why the first clunky drum fill in "Iron Man" is an outstanding human achievement. I almost always lose.
At the same time, I hesitate to say anything definitively sucks. Opinions are sometimes misconstrued as facts, but they are quite opposite; They are an analysis through the filter of one's personal perception of cool, devoid of the concept of good. The job of music publications such as this one is to inform about what is happening and opine about what has happened. Sometimes people get miffed at RFT for not covering St. Louis bands who have followings, but that none of the writers particularly have interest in. These folks don't realize that part of RFT's role is to highlight the cool artists, not just the good ones. And no amount of Pop's ticket sales or Twitter followers can make a bad local nu-metal band cool.