Men are vain creatures who worry, maybe excessively, about beauty and keeping up with standards of beauty set by society.

vain 是形容词，意思是"虚荣的、自负的"，形容过分关注外表或他人评价的心理状态。这个词来自拉丁语 vanus（空的、无价值的），暗示虚荣心是空洞无意义的追求。