gmaxwell is a core developer, he got a better badge [] than the "book" bitcoin expert badge.
Look at the left side (Under the coins) of his latest post: https://bitcointalk.org/index.php?topic=3069524.msg31735429#msg31735429

achow101 is the best nominee to this list, he can accurately point out and correct mistakes from the member's replies and posts in the D&TD Board.