1. A method comprising: monitoring data traffic in a data network via an electronic interface with the data network, wherein monitoring comprises monitoring data packets traversing the data network at an appliance that is logically disposed between an end-point device and the Internet; calculating a first conditional probability that content in first given data traffic being monitored is malicious; calculating a second conditional probability that content in second given data traffic being monitored is malicious; ranking the first and second conditional probabilities with respect to each other resulting in ranked conditional probabilities; and performing at least one of anti-virus or anti-malware scanning of the content of the first or second given data traffic depending on whose conditional probability is ranked higher in the ranked conditional probabilities to the exclusion of the other of the first or second given data traffic; selecting a first one of a plurality of scanners for performing the at least one of anti-virus or anti-malware scanning, wherein selecting is based on an efficacy value associated with respective ones of the plurality of scanners for a given type of content that is being carried by the first or second given data traffic whose conditional probability is ranked higher in the ranked conditional probabilities; selecting a second one of the plurality of scanners for a performing a subsequent operation of performing at least one of anti-virus or anti-malware scanning after scanning by the first one of the plurality of scanners, wherein selecting of the second one of the plurality of scanners is based on a conditional probability that the second one of the plurality of scanners can catch malicious content not caught by the first one of the plurality of scanners, wherein a same content of the first or second given data traffic is processed by the first one of a plurality of scanners and the second one of a plurality of scanners, and wherein selecting the first one of a plurality of scanners is based on a data type of the content of the first or second given data traffic.