I think comedy nerds are just people who see comedy as an art form, and therefore don't necessarily have a specific, narrow sense of humor but rather a broad range of kinds of humor they can find funny, because they are able to see the comedian's intention and execution of a joke. Rather than simply reacting to a joke with, "That's funny/not funny" based on their specific type of humor that they enjoy, comedy nerds are more analytical and respond to jokes with something like, "That was well done" or, "That was obvious and poorly delivered".
It's very similar to being a music nerd. Music nerds don't describe themselves as having specific "taste" in regards to genre or style of music, they just see good and bad music, derivative or inventive, skilled or unskilled playing, etc.