I too am worried about being judged by YC Alumni, much like I worry about being judged by geeks in general. Even though I'm a geek myself (coding for 2/3rd my lifetime, Ph.D. in comp sci, etc.), people usually mistake me for an artist, and that works against me initially. (Later on, when they get to know me, it turns around and they're like: "Oh, it's good you're so well-rounded", but only if I can overcome the initial prejudice.)

The YC application reads like they want to judge you based upon your potential and breadth of experience. I focused in my application on showing my diverse background, and how I don't fit into a standard mold. My concern too is that YC Alumni might be subconciously be like: "We look for people who don't fit into a standard mold, but only ones that fit into a certain mold of not fitting into a certain mold."