Today, more and more information provider such as digital libraries offer corpora related to a specialized domain. Beyond simple keyword based searches the resulting information systems often rely on entity centered searches. For being able to offer this kind of search, a high quality document processing is essential. In addition, information systems more and more have to rely on semantic techniques during the workflows of metadata generation, search and navigational access. But, due to the statistical and/or collaborative nature of such techniques, the underlying quality of automatically generated metadata is questionable. Thus, the quality assessment of information system?s metadata annotations used for subsequent querying of collections has to be guaranteed. In this paper we discuss the importance of metadata quality assessment for information systems and the chances gained out of controlled and guaranteed quality.