Is short (masculine-length, e.g., above the collar).
An old saying is that 'women with small chests shouldn't have short hair, unless they like being called "Sir" a lot'. I concur. Likewise, men, especially those under 5'10" tall who don't have substantial visible biceps, arguably shouldn't have long hair unless they like being called "Miss" every so often. I used to know a guy who would say with a straight face to hippies, "Excuse me, do you have the time, Miss?", but then, he's 6'4" and a weightlifter, and physically rather prepossessing.
Oh, and adding large amounts of facial hair and/or tatoos aren't IMO really adequate approaches for avoiding this likelihood of a male being misapprehended as a woman if he chooses for some reason to wear hair length historically associated with traditional, feminine women. Both can result in additional negative appraisal, not to mention more and more women (especially the lower-class sort, socio-economically or at least WRT how ladylike they comport their lives) are sporting tatoos these days. BTW, for those of you living in cold climates, the research has been done. Facial hair doesn't actually help with cold temps very much; certainly not enough to make up for the price it carries in increased difficulty in maintaining good hygiene.