Gray Matter
It is an open question whether or not a prospective applicant for a job should dye his gray hair. On the one hand, it would give him a youthful appearance. Perhaps he would appear to be a more energetic person.
Marriage
Marrying Off a Daughter to an Older Man in the Gemara
The Gemara's warning against marrying a young daughter to a much older man, and whether the match is allowed when she agrees to it.