tl;dr'd the rest of the thread, but this guy's being truthful. I wince at calling it a code of honor, but I suppose that's what it is. Other than that, it's also good business. You don't just sling drinks, you also make people feel safe and comfortable. At home, so to speak. It's what keeps them coming back. Small-talk and the usual pint-bottom philosophy are a significant part of the job. And gossiping to non-coworkers is an absolute no-no, since it'll detract from the feeling of security the place gives. Which will, without exception, show on the income.
At the same time, though, bartenders have to maintain a distance. Be formal on first meetings. Be politically correct, and steer discussion away from 'sensitive' subjects. Keep your sexual orientation under wraps, whether gay or straight. You'll have women buzzing around you every hour of the day, and since you will without exception be the sharpest fellow in the bar, temptations will be constant. But keep it professional. Never give your surname, or at least use an alias - people sometimes do unsavory things when drunk, and sometimes the unsavory things escalate to the point that they'll follow you home if they know where to look. No skimming, taking advantage of over-inebriated clients, or any other shenanigans. Those end carreers.
The list goes on for a while from here, but I suspect people will get the idea.