Clustering is an unsupervised learning technique used to group a set of elements into nonoverlapping clusters based on some predefined dissimilarity function. In our context, we rely on clustering algorithms to extract points of interest in human mobility as an inference attack for quantifying the impact of the privacy breach. Thus, we focus on the input parameters selection for the clustering algorithm, which is not a trivial task due to the direct impact of these parameters in the result of the attack. Namely, if we use too relax parameters we will have too many point of interest but if we use a too restrictive set of parameters, we will find too few groups. Accordingly, to solve this problem, we propose a method to select the best parameters to extract the optimal number of POIs based on quality metrics.