I was chatting with an old classmate at a homecoming a few months ago, and he mentioned that, during the polygraph top get Canadian Top Secret clearance for a co-op job, he had to say how many drinks he had each week. Being a university student, it got brushed aside, but the answer was considered to be alcoholism-level.
In a weird way, that's almost a positive sign, if you view the security-clearance process as mostly being about quickly clearing away secrets that could be used for blackmail down the line, when the person has more authority and more to lose.