The gemara Nazir 2a quotes a baraisa saying that
כל הרואה סוטה בקלקולה יזיר עצמו מן היין
Anyone who sees a sota in her disgrace (would/should) swear off wine.
The word יזיר, as I understand it could just as well express "would swear off..." or "should swear off..." Artscroll indicates the grammatical mode of this line, quoted in Rash"i's commentary on B'midbar 6:2, as "should". It is also translated as such in the opening lines of the Artscroll g'mara in both masechtos Nazir and Sota. However, one footnote in Artscroll's elucidation on Nazir 2 takes for granted that it means "would want to..."
Is the quoted baraisa giving a prescription to those who witness the unfortunate plight of the sota or is it describing the instinctive reaction one is likely to have upon seeing the same?
NOTE: I always understood it as "would", as that would fit with the fact that this is quoted as an answer to the question "why are these topics juxtaposed?" I see now that "should" would fit almost as well, but I am not convinced and I'm really not sure how to prove one way or the other without external evidence.