This video study of dating-age adult men and women interacting at a “bar” mixer set up by the researchers will educate and creep you out with all the body language indicators that we men are clueless about.
Body Language - Indicators of Interest (IOIs)
https://www.youtube.com/watch?v=SBOtj1RmaUE
I don’t think we are clueless about them, just not very consciously aware of them. We must be aware of them on some level, or they wouldn’t have any effect, and women wouldn’t be using them.