The importance of detail and complexity is discussed in relation to the model building process in ecology. An example model for rabies in foxes depicts how less detail in the model could generate complex results. Particularly, the common issue of errors in the immunisation coverage is investigated. An astonishing result discovers, that randomly distributed errors support the success of immunisation compared to a perfect error free scenario. As a consequence the classical pair of model classification into strategic and tactic models is questioned. Eventually it is shown how relating details to model structure and complexity exclusively to model results will discover an ideal model depending on the modelling purpose of a study.