>>>- Through direct connection i.e. no firewall or NAT translation (either extreme user ignorance or user should have known better)
>>
>>If they really exist, no defense of behaviour. I think more of a straw man than significant percentage found.
>
>Some connections especially business come with more than one IPv4 address. I can imagine someone deciding to "make good use" of an unused IP with something like this.

Having a hard time to visualize this... several land lines, in ase 1 provider has virus ? Makes only sense with a router ditributing load across several WAN ports. Company already has 9 discrete physical servers and the "plan" of rackspace for 12 boxes is cheaper than 9 single boxes ?