Purpose: The purpose of this paper is to provide a quantitative analysis of the "messiness" of the social tags in folksonomies to see how useful they might be for general search and retrieval in library catalogs. Design/methodology/approach: The study harvested tags for ten books from LibraryThing measuring characteristics which would hinder search and retrieval in library catalogs. Findings: Because there are no rules governing the way people tag, folksonomies suffer from a certain degree of messiness and inconsistency. More than a third of this messiness is in the form of tag variations followed by tags containing non-alphabetic characters. The other types of messiness measured were less significant, making tag variations the most prominent hindrance to search and retrieval. Originality/value: The paper supplies quantitative support for giving users guidance for creating tags in a library catalog. However, libraries should remember that part of the attraction of social tagging is its open and self-created environment and that too many rules and regulations may discourage participation. © Emerald Group Publishing Limited.