The Mishnayot in our perek offer a list of common expressions that are to be understood according to their accepted meaning. For example, someone who says “I vow not to benefit from anyone who lives on dry land (yoshvei yabashah)” is understood to mean that he will derive no benefit from anyone – even if they are professional sailors whose home is on the sea – since every human being is considered a land dweller. If he says, “I vow not to benefit from anyone who the sun sees (ro’ei ha-hamah)” he cannot derive benefit even from blind people, because they, too are seen by the sun.
One interesting case is where a person vows not to benefit from people with dark heads (shehorei harosh) which is understood to obligate him to avoid benefiting from men (even if they are bald or white haired), but permits him to benefit from women and children. The Gemara explains that the term is understood as referring specifically to men because women always keep their hair covered and children never keep their hair covered. Men, who sometimes cover their hair and sometimes do not, are the ones who fit into this category. What is clear about this expression is that this is not an actual description of a group of people, but a general expression that refers to men. In fact, we find in early Babylonian literature that the term shehorei harosh was a popular colorful expression that meant “males.” It is likely that usage was borrowed in other neighboring cultures and languages, as well.
The fact that the Gemara mentions in passing that men sometimes keep their hair covered and sometimes do not would appear to support the position of those who believe (like the Gra, the Maharshal and others) that Jewish men are not obligated to cover their heads, and do so for reasons of tradition, not for reasons of halakha. Others argue that this Gemara is not a proof for that position, since the Gemara can be understood as saying that men do not cover their hair completely, in contrast to women for whom complete hair covering is viewed as laudatory if not obligatory.