NuclearShadow :
If you really believe such, if you truly believe the average military including the US is full of scum. Then why do you suppose any order would be able to be maintained within the military? This wouldn't be possible. I will agree that a poor person is more likely to join but that is because its a opportunity to get out of poverty and one that is of a noble cause. If anything this is a good thing and to top it off it gives this person a opportunity further their education which is unlikely that they would be able to otherwise.
As for criminals/gang members joining, yes there is a very small amount that join that are still loyal to a outside gang. This however is not a large part of the military.
Also there are former criminals and gang members in military, but isn't this a good thing? People that turned their lives around and actually became a positive for the entire nation they serve instead of a burden? I would much rather give a kid a chance at a good future that they could look back on and be proud of themselves than to have them in prison. As for the intelligence level of the men and women who are serving and have served, sure we are more average. I certainly don't feel that I am more intelligent than everyone else.
I did not say "full of scum", I said scum is more prevalent in the military than in the general population (say 10-20% against say 5% in the general population, which still means that 80-90% are not scum). Order is maintained through far more stringent regulations than in civilian society so there being order in the military doesn't prove anything and for example, rape is still twice as common in the military as in the general population.
The FBI suspects 1-2% of all American military personnel to be members of a gang, this is far higher than in the general population. Contributing factors to scumlevels in the military are: 1) gender, men are more likely to be criminals/scum, most people in the military (many more than in the general population) are men, 2) age, young people are more likely to be criminals/scum, most people in the military (many more than in the general population) are young, 3) pay/qualifications, the lower ranks (who make up the majority of the military) consist of low-paid, low qualification jobs, but with more benefits than other such jobs and hence will attract more people from poor neighbourhoods, where people are more likely to have a criminal background (officially the military refuses people with severe criminal records, unofficially it will sign waivers and admit them to meet recruitment quota's), 4) the blow-stuff-up/killing-them-ragheads factor of the military which attracts people with extremist ideas and/or volatile personalities: the Timothy Mc Veighs (who actually did serve) and supremacists/neo-nazis of this world, 5) war traumas transform otherwise upstanding citizens in unpredictable and dangerous deranged individuals, many of them still "serve" for months or years while in this state.
Now you will find the same pattern in most militaries; the Russian military and many African militaries are worse than the US military, the UK military might be comparable while the Japanese or Northern European militaries are probably less problematic (though even here in Northern Europe many cases of soldiers engaging in assault or rape are known), but all of them do attract some of the worst people in their respective societies, even though I'm sure the majority are upstanding citizens, or at least average. So no, militaries definitely are not the "best" sector of their societies and certainly not the brightest (yes special forces, technicians, doctors and some senior officers are but they constitute a very small portion of the entire military).