If someone won't make the effort to actually seek out more examples of a genre before instantly writing it off based on one or two songs, they don't deserve to have their opinion heard.
Guess that's where we disagree. We make instant decisions all day, and as Gladwell points out in Blink
most of the time when we "spend more time seeking out other examples" it usually leads to just solidify our original decision in the first place. Not always, but most of the time. Even so, they still deserve to voice their personal opinion.