Sucking on a girls toes is like a precursor to going down on her. If a girl relaxes and enjoys having her toes sucked on, then you can work your way up the legs to your final goal. Another way to put it. The feet are like the starting place of a womans legs, which are very sexy. The legs then lead up towards her crotch(sp?). Somehow, when a guy looks at a womans feet, its like the starting point from which he can run his gaze up her legs and to her hips and ass. Personally, I have a big foot fetish, leg fetish, ass fetish, and they are all tied together some how.... I well, I hope that explained something.... Don't know what...