Since international awareness of a global rush for land has grown from 2008 onward, various databases and reports have attempted to provide an overview of the situation by compiling information on individual land deals. While providing such an overview is challenging owing to the dynamic and untransparent nature of the investments, flawed methods of using and citing data are aggravating that challenge and allowing dissemination of inaccurate information. The consequences are an unnecessarily blurred picture of the land deal situation and thus an inadequate basis for related political decisions or social actions and a misleading starting point for new research projects. In this article we demonstrate some of the flaws in the use of data and their consequences, with examples from fieldwork and literature on Tanzania. The paper illustrates and contributes to the evolving debate on appropriate research methodologies for studying the global land rush.