In this paper we want to explore the epistemological relevance and value of reputation understood as evaluative social information. Using reputation to classify and assess an agent or an item can be epistemologically useful in the absence or - as is especially relevant today - overabundance of information. However, in order to be and remain epistemically useful and ethically just it has to be open to constant scrutiny and revision. We will introduce a model of rational consensus as an example for the rational use of reputation for epistemic purpose before analyzing different reputational tools on the Web. We will conclude our paper with a critical comment on the potential danger of using social information to evaluate information and knowledge claims, resp. to warn from epistemic injustices on the Web and elsewhere.