an infected vm is no victim. Lets say you downloaded a pirated game which also has malware in it. You play said game in a vm specifically made _for_ that game. So the malware only runs when you are actually using the vm.
You'd have a vm for each specific piece of software that is untrustworthy, and sharing of files can occur thru sanctioned channels (such as a local, safe temp directory shared by each vm, or read only mounts).