> It's as if there's a line between actively lying ("Studies show that men who buy this car will find many many women attracted to them") and just putting it there suggestively

I doubt pretty girls in ads are actually supposed to mean the goods they advertise make a man more attractive. Who (except teens) would believe that, consciously or subconsciously? You just get attracted yourself and that's enough, simply seeing a pretty girl fires the hormones and neurotransmitters making you feel good about what she advertises, no semantic load necessary.