Three things are absolutely necessary when going to a meet: 5 personal CDs and paper and pen.
You know your music. You slip it in to the player. You take notes. Change the CD, take more notes. Move over to another piece of equipment, slip in your music and take notes.
It just may be that certtain people do not like taking notes. But how hard can it be to say, "I like it," I like it more," or "I like it less"?
No, 5 CDs from Britney Spears will probably not make it, nor would 5 recordings from the same company, like Sony. It would help if you had a nice mix of music, like The Three Tenors singing Nassun Dorma, a little Sade, some rock guitar, The Unfinished Symphony, and some bluegrass; just a nice mix of music. But I bet a lot of newbies only have one type of music, so they have to be exposed to others' musical tastes. And since they are not 'familiar' with others' music, can they do a valid review? Well you could if they sounded distorted, compressed, clipped, bass heavy, bass shy, bright, muted, neutral, etc.
I think everyone should inject a mini headphone review of whatever is hanging around, especially when Head-Fi starts to slow down. Just do it, posit it, and forget it. The "Best Headphones under $500" is a great place for mini-reviews as you are bieng asked to put down your personal impressions.