No doubt BKF would get rid of this stuff quite easily. I've just always been wary of using it on the inside of my fermentors (I do go to town with that stuff on my kettles though, makes them look brand new).
I ferment in kegs, I hope there's none of this kind of crap in there I can't see. Are you noticing any subtle off flavors in your beers?
I have seen it in my corny keg fermentors. If it's there, you should be able to see it with a flashlight. It also has kind of a rough texture that is pretty noticeable.
No, I haven't experienced any off flavors, and none have been mentioned by any judges.