Lately I've been thinking about how to vet quickly and ruthlessly, and I've come up with something: watch his facial expressions SUPER closely, and listen if his voice changes pitch.

Micro-expressions are fleeting glimpses of how someone really thinks and feels, from an upturned lip twitch (contempt, disgust, dislike), to the eyebrow flash (big indicator of openness, I like you, recognition -- as a retired teacher, we are inveterate, promiscuous eyebrow flashers! HA!) Reading up on micro-expressions is an education in itself.

Out in the wild, I've come to see the following, and I'd be fascinated for others to chime in with their observations:

-- eyes glossing over me, eliding my very presence, not even seeing me as a body, much less a person: quite often fatphobic, and/or has a low opinion of overweight women, or less than perfect women, edited to add short and/or older women, too

-- giving more attention, looking at me more when I'm made up or dressed well: shallow

-- never really looking me in the eye, looking everywhere else: I don't exist as an actual human, he's bored, preoccupied, not interested, shallow, bad listener

-- keeps running into me, or bumps/bonks into me way too much: oblivious of personal space, entitled to more space than he reasonably needs

-- that smirk, especially when talking about things that aren't particularly funny: entitled, dismissive, avoidant, afraid, arrogant, and always insecure

-- eyes narrowed, especially when I talk about myself, my interests, my doing something I was proud of, even something as benign as creating a gallery wall or learning how better to do something: jealousy, anger, insecurity

Other ways that you've found that a man's expressions give them away? Can also include voice changes, too.