Monstrous behaviors are often implicitly defined as opposed to normal behaviors but hydrologists often forget to define what they do consider as normal. We argue here that, in hydrology, there is no such thing as a normal behavior, and that the judgement that we can make on any behavior will depend on an implicit or explicit reference. We show here that when using as reference two very different models - a rainfall-runoff model and a neighbor-based model - we reduce significantly the number of catchments falling in the 'monsters' category.