Hairy legs.
There, I said it.
As I get older, I find that I add more and more to the list.
Belief or active participation in Christianity or any religious delusions; pseudoscientific woo such as homeopathy, ghosts, metaphysical healing, magic rocks, dowsing or any form of scrying; an unhealthy obsession with television, "alternative history", Ancient Aliens and the like; adherence to conspiracy theories and "false flag" narratives (if we're at dinner and you tell me Sandy Hook was fake, I will ditch you at the restaurant); and any display of the circular ignorance that leads people to vote for someone like Donald Trump.
Also, if I detect an inability to achieve any level of intimacy, problems like drug addiction or substance dependancy, or the tendency to derive pleasure from hurting others, we're done. Life is too short for that.
That's all that comes to mind right now, but I'm sure I'll think of more.
Non smokers, lack of concern about their body (except the lungs), ignorance, conceit, egotistical, controlling.
Surprise me and let's see if you can handle the other me.