Maybe it's because I've held a Top Secret security clearance once...

[Munificence]

48. In my

debriefing in the early 90's I was not informed that I could not mention the clearance. I was however told that if I reveled what type of functions I performed outside of my MOS assigned to me that the Army would deny it and that I never existed within the program. They never really once told me that I could not mention the program after I ETS'd, but instead that they would deny it or I ever existed, they asked me to not discuss the details but I could state that I was in "Special Weapons". Now while I was in the program I was not permitted to discuss it with civilians and only a select few other soldiers in the chain of command.

I used my clearance credentials on my resume in the past even though my clearance had expired. I think ones ability to obtain this level of clearance speaks a lot about a person in the civilian world when it comes to finding a job, however it appears that we are not as stringent today as we were back in the 80's in passing out security clearances!