Party cues provide citizens with low-cost information about their representatives' policy positions. But what happens when elected officials deviate from the party line? Relying on the 2006 Cooperative Congressional Election Study (CCES), we examine citizens' knowledge of their senators' positions on seven high-profile roll-call votes. We find that although politically interested citizens are the group most likely to know their senator's position when she votes with the party, they are also the group most likely to incorrectly identify their senator's position when she votes against her party. The results indicate that when heuristics "go bad," it is the norm for the most attentive segment of the public to become the most misinformed, revealing an important drawback to heuristic use.