I lean toward Robert’s view, with reservations. Students who are going to read modern literature at all, starting with Joyce and Lawrence, can scarcely avoid contact with explicit description of sex. But it may be something a teacher might want to consider in preparing a course–how many books of this type, the makeup and level of maturity of the class, the aims of the course, etc. I mentioned Updike’s explicitness in my post because sometimes, someone who has taken a recommendation from me to read something will say later, you didn’t warn me about that!
But I disagree with Mike Potemra’s Corner post somewhat, on the idea that explicit sex in Updike is a matter of glorying in the completeness of God’s creation. That is true to a degree, but I think there is also some desire on Updike’s part to make us wary of it: that it can lead to emptiness, and that if you make too much of the body and its pleasures, you will soon be trapped in the body’s pain and deterioriation. This is happening more and more as our outstanding novelists grow old. Recent Roth novels are showing this too. It may be unintended in some cases.