Fortunately, most of the effects are easy to notice, especially in a replay.The circle shows no stat gains if you manage an all-negative setup, which could be achieved by having 3 pieces of equipment with greater stat drawbacks than gains in favor of a specialized bonus like easier perfect shielding. That would possibly slip by unless you actually look at the character setup.
Worst comes to worst, for online events we can scan the replay files for equipment with a simple automated tool. It doesn't exist today, but it'd be pretty easy to do.