Simulation is universally considered the most effective method of designing and evaluating new network protocols. When developing protocols for mobile networking, the chosen mobility model is one of the key determinants in the success of an accurate simulation. The main role of a mobility model is to mimic the movement behaviors of actual users. Several mobility models, with widely differing characteristics, are employed in contemporary simulation-supported research. Some are simple but far from representative of real user movement patterns, while others provide more complex and realistic modeling. Given the critical role of the mobility model in supporting realistic and accurate protocol simulations, its correct design and selection is essential. In this paper we critique a number of recent mobility models.