I can tell you what I'm NOT attracted to style wise. The frat boy look *ugh* it really is a turn off to me. You know, the long slogan t-shirts, the multipocketed khaki, or brown, or khaki long shorts, wearing either flip flops or those what I call "Calvin" shoes that are bulky with their ankle socks.
LOL, you just described my little brother PERFECTLY. He's not a dick though.
Or my most unfavorite, a short sleeved collared shirt with open with a t-shirt underneath. Sometimes they wear a cap, which just makes them look worse to me.
Ahh well there is actually some functionality to this. You see, when a man like me is of the larger persuasion, we tend to work in a field that requires "business casual" attire. Ergo, the polo. However, it is incredibly dorky to button up ALL the buttons, so the style is to leave the top one undone. It is also very...70s-porn-star...to have an open shirt with your chest hairs sticking out. It's quite gross actually. The t-shirt serves two functions: one, it cleans up the look and avoids the "showing off" of unsightly chest hair. two, it keeps our nipples from poking out and becoming the talk of the office. You could say that the undershirt is almost a man bra, more like a man training bra.