Just capturing some thoughts we were discussing on the reddit and this is somewhat related to the white-blacklist-add-reason-field feature request.
Basically it'd be really nice to be able to browse blocked domains and get an idea of why they've been blocked. As a new end-user, I've really enjoyed using pi-hole for many reasons, but I'd love the ability to easily educate myself and interpret the dashboard's blocked domain list more rapidly.
At its fullest version, the dashboard might include small document icons with tooltips next to domains that have been white/black listed, showing a brief standard format summary of why they were listed, and allowing users to click through to pages providing more detailed information on how that domain (and associated domains/subdomains) is used and why it's typically blocked/approved, similar to the information pages you can find on identified viruses.
I suppose this could be implemented either on a more ad hoc list-specific basis (e.g. the "reason" field for a given domain in a given list), or as a centralized wiki-style database that would lookup listed domains as unique keys to pull the relevant domain information.