[mothered]

And of course there are always infected programs with little to no detection ratio (although somewhat rare), so a simple virus scan is not always a surefire way to see if a file is safe or not.

Definitely so.

I can crypt a file (FUD), thereby It will bypass any heuristic analysis an AV may perform, and It will not be defined In the vendor's signature database definitions. As a result, both the virus scan report and runtime analysis will not show any detections.