Previous research on point spread betting often assumed that bookmakers attract an equal volume of bets on either side of games in order to maximize profits. This paper examines the plausibility of this assumption. Financial simulations based on actual bet volumes on NFL games, point spreads, and game outcomes over the 2005-2008 NFL seasons indicate that unbalanced betting generated positive profits for book makers, including profits larger than would have been made if the betting volume was balanced on all games.