Sniffing is cost-efficient and trouble-less method for capturing Wi-Fi traces within an area of interest. However, a sniffer is likely to miss Wi-Fi packets because of inherent characteristics of the wireless medium, resulting in incomplete traces. In this paper, we investigate the completeness of Wi-Fi capture using sniffers and conduct experimental measurements to support our analyses. We collect Wi-Fi traces using ten co-located sniffers while moving the source node away in steps of ten meters. As expected, individual sniffers lead to low completeness. This motivates the study of completeness using redundant sniffers. Our experiments reveal that a certain gain in completeness is achieved even when the source node is far from the sniffers.