Believe it or not, researches actually did a study on this.
They showed a picture of bodybuilders and regular men to women, then they tracked their eyes to see where they spent the most time looking. They found that women would look at the bodybuilders much more then the regular guys.
They also found that they would first look at the chest, followed closely by the abs. Then their eyes would go towards the shoulders and finally the arms.
They did also spend time looking at the guy's package, but I can't remember where that ranked.