A lot of it boils down to the fact that anti-virus vendors pretty thoroughly lost the war quite some time ago. Almost by their definition, signature tools are b

A lot of it boils down to the fact that anti-virus vendors pretty thoroughly lost the war quite some time ago. Almost by their definition, signature tools are busy detecting the last generation of threats while everyone has moved on. You can, after all, check your code against all the AV engines before you ever let it out. Most heuristic engines aren't in much better shape. In the end, these types of software are more about providing a security blanket than anything else, the world is pretty ugly out there and few people have anything better to offer an individual.