Just my .02 here but if an interviewer asked if I ever 'failed a checkride' and I had failed an instrument check or NATOPs check(or AF equivalent) in the past, I'd pipe up and tell him/her I did and why and what I learned from it. Heaven forbid it would come up in conversation with a former squadronmate who's on the property and knows of the busted checkride. Same holds true for an application IMHO.