Open data are considered an essential resource for governments, businesses, and citizens. In that context, open data portals have potential for creating enormous economic growth. Open data portals should allow the reuse of open data, ensure the efficiency of data transmission, and enable professional initiatives based on data reuse. However, there are portals that are inefficient because they do not allow reuse of their data. The objective of this work is to define and identify open data portals that do not offer the possibility for professional reuse of their data. We refer to them as “pretender open data portals”. The following research questions are considered herein: What minimum criteria must an open data portal satisfy to enable professional reuse of open data? How can portals that do not meet these criteria be identified? And, what problems might these portals present, and how they might be solved? The results of an analysis of two samples of open data portals in Spain reveal that 63.8% and 56.1% of the portals analyzed in 2019 and 2021, respectively, can be considered pretender open data portals. The existence of pretender open data portals can have negative economic and social impacts, such as wasting public resources and projecting a negative image of the government’s open data policies. To find coordination mechanisms to develop open data portals that, through the professional re-use of their data can create economic and social value, is one important challenge. The analysis of best practices of open data portals can be also a way to go in deep in the understanding of open data reuse impact not only from a professional standpoint.