Crowbar's hit it on the head, but as a warning, I'd advise against lumping everyone in together. One of the best LCpls I had working for me back in the day had enlisted specifically to ease his way into OCS, because he was a dumbass in college (bad grades from too much beer). This person is now an F-18 pilot and a Capt (so now he tells ME what to do), and we still talk via email pretty regularly. He's still one motivated SOB, too.
Being a good Officer (Marines, Navy, or otherwise) isn't about having a Good Conduct Medal or not. It's about giving a damn--about the mission, your execution of it, your people, etc. Your Marines/Sailors/Soldiers/Airmen/whatever can tell the difference between a good Officer and a sh!thead, plain and simple. Lead by example, know your job, your subordinates' jobs (at least how hard they are), ask intelligent questions, and you'll be off to a good start.