You probably could be influenced irrationally by them, yes. To further clarify, you would probably more readily accept the view of a curvy, symmetrical woman without further evidence than that of a flat, asymmetric one. If this is a primary influence, you're probably not the best target for rationality training.

You are missing the point. Ceteris paribus, I end up enjoying relationships both long term and short term with women that have curvy figures and symmetrical faces more than with those who don't.

I might end up behaving disproportionately to the real strength of this signal, but before singling this out as a great irrationality that it is supposedly unethical to "exploit" me by using to plan your behaviour towards me, ask yourself if this is that much big a deal. Consider that we often overestimate the strength of signals like education, taste in music, intelligence, religious convictions, political stances, nationality or hair colour when it comes to picking mates.

Also if people genuinely crave X, but overestimate their utility gained from X, why in the world is it unethical to still optimize for X? I mean people are better of than if I hadn't, they just aren't as much better off as they thought they would be.