I would imagine most DDNS services push traffic to a blacklisted node. Your ISP blacklists the D-IP so that you, as a lowly end-user, can't run something like

I would imagine most DDNS services push traffic to a blacklisted node. Your ISP blacklists the D-IP so that you, as a lowly end-user, can't run something like an email server. So, I would imagine effectively sorting out which IP addresses are blacklisted because of malware infection or simply ISP infection would be very hard indeed...