The critics of The Guardian are engaged in a lively debate on the topic "Can critics and artists be friends?" As Tom Service notes, American attitudes on this subject tend to be stricter than British attitudes. The late Harold Schonberg, during his long reign at the New York Times, forbade even the slightest hint of critic-musician fraternization, and also prevented composers from working as critics at the paper. I believe that such policies were misguided, emblematic of a sort of Cold War emergency seriousness in the arts arena, and they led to criticism that was not as smart or strong as it could have been. For, as many participants in the Guardian debate point out, knowing how artists think and work can greatly deepen a critic's perspective.
That said, I generally avoid meeting the people I write about. I tend to write profiles only of artists whom I've long admired, or with whom I feel a strong identification. I was an avid fan of John Adams for more than ten years before I met him — my college roommates were subjected to days and nights of Nixon in China — and I don't think meeting him changed how I heard his music. The same goes for Esa-Pekka Salonen, whom I'm writing about now. I'm with Andrew Clements in thinking differently about composers in general: I'm biased toward them as a species, having tried to write music myself. They are at the center of my work, and I need to know what they are thinking.
The irony underlying this discussion is that some of our strongest prejudices — favorable or unfavorable — are directed toward people we've never met. Lack of contact lets us idolize our heroes and demonize our foes. The advantage of meeting people within the profession is that you see them as they really are. The danger is that you may end up liking a lot of them, tolerating most of the others, and madly loving rather few. For myself, I want to preserve at least some of the fantasy of fandom.