I’ve held a security clearance since 1990, and you’re way off as far as drug use. I’ve known at least one guy who had been a pot dealer and had no trouble getting a TS clearance. Knew another who, when filling out a questionnaire on which drugs you’ve done, complained to the administrators that “they’re not all on here.”
As long as you are honest about past drug use, they don’t care what you’ve done.
I’m not certain about misdemeanor convictions, but the general rule is that unless you lie, or have some secret you could be blackmailed over, they don’t much care what you’ve done.
However, my opinion is that they African Americans tend to join the Army more for reasons of self-improvement or to get out of bad home life, avoid gangs, etc rather than any kind of machismo or being gung-ho. So many cannot pass the high test scores or physical qualifications (yes, including swimming ability) or just don’t have the inclination.
More Whites join due to family tradition (especially in the South) or wanting to prove themselves and kick ass.
I am way over generalizing, of course.