  We develop a model of content filtering as a game between the filter and the
content consumer, where the latter incurs information costs for examining the
content. Motivating examples include censoring misinformation, spam/phish
filtering, and recommender systems. When the attacker is exogenous, we show
that improving the filter's quality is weakly Pareto improving, but has no
impact on equilibrium payoffs until the filter becomes sufficiently accurate.
Further, if the filter does not internalize the information costs, its lack of
commitment power may render it useless and lead to inefficient outcomes. When
the attacker is also strategic, improvements to filter quality may sometimes
decrease equilibrium payoffs.
