The shoes - You need to look your best in an interview. That should be obvious. The kid was an idiot. He was a bigger idiot for bragging about his scuffed up shoes.

The suit - You need to dress the part. I'm saving up to buy a $200 suit from JCPenney, but I only make $40,000 a year and we're on a tight budget. Once I'm making $100,000 a year, I'll upgrade to $500-600 suits. When I'm making $250,000 or more, then I might splurge and get a $1,000 suit for special occasions. He needs to dress to what the job is required. If he can't afford that yet, he should explain he'll buy a nice suit once he can afford it, and not argue with you about it. And I can certainly tell the difference between a $200 suit and a $1000 suit, and I know little about suits.

The arguing - He should never have argued with you during an interview. Even if he disagreed with you, he still shouldn't argue with you. This tells you 2 things: he's an idiot and he's going to be arguing with you often about stupid things.

The mission - I think when you bring things up during the interview, you bring up your most recent big accomplishments. If you're getting into grad school or med school, yeah, you might bring it up, but hopefully what you've accomplished during your undergrad is bigger and better than what you did on your mission. If this is your first job, you bring up what you accomplished in school. If it isn't your first job, you're not going to be talking about school accomplishments, you're going to be talking about your internship or your recent job experience. If your biggest selling point is something you did 5-10 years ago and nothing you've done since is worth mentioning, then you've got a career crisis.

Guys go on missions for a variety of reasons: to serve the Lord, to help people, because of parent pressure, because they were promised a car, or their girlfriend won't marry them unless they go, etc. There's a variety of reasons. But once you're out there, the reason you STAY is what's most important. In my opinion, those who go on missions for the best reasons (to serve the Lord and those in need) don't brag about going on a mission. They're willing to talk about it and what a great experience it was. But it's not about what they did, it's about how blessed they were to have that opportunity.