Spilled Expresso

Today was my third day of training at my new job as a cashier and sales associate at Serendipity restaurant and general store in Manhattan. one of my coworkers is kind of a jerk. This guy is 25, and only three years older than me. Today, he said something that really irritated me, after I commented on his rudeness towards my fellow female coworkers and I, he said "I don't have to be nice to you guys, I don't get with people I work with, so I have no reason to be polite to you." He went on to insist that when he likes a girl he treats her nicer than she ever dreamed of being treated. "I only act like this at work," he said.
Now the guy in question is not a complete prick. He can be nice, however, he is frequently rude, and arrogant. It is not that i care what he thinks of me, I could care less about whether he likes me or not. However, I feel he should treat us with respect anyway, whether he wants to "get with us" or not. Why is it that people save what should be common human decency--as human behavior reserved only for people who's pants they want to get in?
While I know many guys (and girls) put on similar acts, i find it nauseating that someone can be so open about this. What difference does it make that this guy is "much nicer outside of worker"? How nice are you if you are only nice to a girl you wanna get ass from?
Not very.
On top of this, this guy has the lamest game ever! He shamelessly checks out and flirts with any girl that walks by. After being called out about this blatant check out, he answered "Girls get self conscious when I don't check them out," Tsch, whatever dude. Equally nauseating, were his lines. Twice he told a girl that he didn't answer them because "he got lost in their eyes." "Girls go crazy when they hear that, you would if you didn't work with me..."
Sadly, the girls he said this too, did seem sickeningly, and surprisingly...flattered. While they seemed to find the line cheesy, the giggle implied that they bought. I imagine that the line would infuriate me and would probably be ignored or meet with a dirty look and snide comment about how many other girls he's said that too. While I often blame girls for falling for such stupid lines, thus encouraging guys to be sleazy, I can't help but wonder how many times, if ever I have fallen for a guy's stupid game.