Malware, phishing, spam etc… are all clear-cut examples of practices the industry would collectively like to extinguish or limit. The audit process for identifying these sites could be pulled from an existing service provider.
Google does incorporate a degree of malware checking in their search algorithm, which could be adopted for the DNSseal purpose.
- See Google Support
Additionally, there are more specialized services like sucuri who focus on malware detection: https://sucuri.net/services
- Appeals Process