We compare three different setups for measuring cell–cell adhesion. We show that the measured strength depends on the type of setup that is used. For identical cells different assays measure different detachment forces. This can be understood from the fact that cell–cell detachment is a global property of the system. We also analyse the role of external force and line tension on contact angle and cell–cell detachment. Comparison with the experiments suggest that viscous forces play an important role in the process. We dedicate this article to Fyl Pincus who for many of us is an example to be followed not only for outstanding science but also for a marvelous human behavior. Graphical abstract