So, I've been noodling with this for a while, and here's where I'm at. Code here: https://github.com/evanp/inaccurate_comparator
Basically, I realized that what I'm looking for is evidence in the output of a "real" difference. And that evidence can be direct or indirect: either I get "A > E" as output, or I get "A > B" and "B > E", which given the transitivity of the (real) operator, is also good.