In the context of increasing concerns about false and deceptive information in public opinion, this research note explores which causes and sources news users associate with the dissemination of misinformation. Based on representative survey data collected in the Netherlands (N = 1,994), we found that news users distinguish unintentional causes related to uncertain evidence and lacking expert knowledge from politically or financially motivated falsehoods. People on the left-wing of the political spectrum associate falsehoods more with the radical-right, whereas those on the right-wing tend to associate misinformation with the radical-left. Right-wing participants, however, are most likely to perceive misinformation as driven by a deliberate attempt to hide reality. Our findings point to an ideological bias in information credibility that could foster polarization along epistemic lines.