Yeah, my fix to this issuethis issue wasn't as effective as it should have been. jadarnel27 is correct in his synopsishis synopsis that the opacity isn't properly reset between successive error responses. I've had a fix for this for a while, but I evidently never committed it.
It is resolved in my local environment, so I'll push it out for waffles to grab later this evening.
Update: I've pushed out a fix, now which just removes the fading nonsense outright. I might rework it later, but I need to tidy up some messes I've made with the JavaScript first.