The research area of very large scale wireless sensor networks made of low-cost sensors is gaining a lot of interest as witnessed by the large number of published papers. The security aspects of such networks are addressed as well, and in particular many security papers investigating the security aspects of such networks make important assumptions about the capabilities of low-cost sensors. Consequently, the techniques proposed in the current literature to provide security properties for this low-cost wireless sensor networks are heavily shaped by such assumptions. In this position paper, we challenge such assumptions by presenting the results of an experiment we conducted using sensors representative of low cost units. And we show that the same security properties can be better provided using techniques based on application-specific knowledge, heuristics and statistical tests. Finally, we show that one of the most highly cited application scenarios to motivate such techniques, the air-dropped sensor network, is likely to be more a myth than a realistic scenario for low-cost sensors.