The need to measure the efficiency of scientific research raises a myriad of questions. There are many different measurement methods and indicators, but none give answers to the general questions like which journal is “better” or which researcher is more effective. It is always necessary to state what we want to measure, for what reason and choose the corresponding measurement process. Whatever measurement method we choose, we need a database to perform measurements and comparisons and generate rankings. This database must be complete in terms of indexed content and validated in terms of metadata because if we draw conclusions by analyzing a too small set or not correct information, the result will not be accurate and some will be disadvantaged, others unduly favored. The Hungarian Scientific Bibliographic Database (MTMT) is an excellent tool for evaluating the results of Hungarian research. Péter Sasvári, a researcher at the National University of Public Service, created a journal ranking of Hungarian journals that are on the accepted journals’ list of the Hungarian Academy of Sciences IX. Section of Economics and Law using the data of this system. The manuscript was published on 31 December 2020 on ResearchGate. We are very pleased with the initiative and hope that MTMT will be increasingly used in research evaluation in the future. However, we illustrate the dangers of incorrect use of MTMT, using the published manuscript as an example. The cause of this is that MTMT is a community product according to the current operating model, therefore it has rather mixed quality records. It should be used with due care in the evaluation. If we organize the workflows around it to ensure the completeness and validation of the incoming records, if we take care of continuous data correction and if we make sure that the statistics used for ratings are based only on validated records, we will see that we have an excellent tool in our hands that can be utilized in many ways and areas.