Appeal to ridicule fallacy.
Indeed, someone here mentioned that Clinton's affair with Lewinsky was consensual. In turn, I pointed out that, just like adult incest, it is consensual but with a power imbalance between the parties.
If you are going to criticize my analogy here, how about you tell me why exactly it is invalid. Also, for the record, another analogy to this can be a teacher/professor having sex with an 18-year-old current student of his or hers. In such a scenario, the relationship and sex would likewise be consensual, but there would still be a power imbalance between the parties.
In such a scenario, do you think that the teacher/professor involved should at the very least resign/be fired from his or her job?
OK, I'll bite.
You are operating under the assumption that any power imbalance equals every other power imbalance. This kind of black/white thinking rarely leads to anything good.
A power imbalance can be many things. Even one party earning more money than the other is inherently a power imbalance - does that make such a relationship unethical? Hardly.
I would argue that it is not necessarily the power imbalance as such that is the problem but rather the nature of the power imbalance and the role conflicts that may arise.
In the teacher/student relationship you mention there is a rather serious role conflict as the teacher is supposed to grade the student AND be the students partner at the same time. That is at least problematic. However, if both parties are adults, I wouldn't say that such a relationship is inherently immoral, but I would say that the education institution is well within its right of forbidding such a relationship and firing the teacher if such a relationship occurs.
More or less the same can be said for boss-secretary type relationship at the workplace.
When I refrain from calling either of those relationships immoral it is both because both parties are adults who can make decisions for themselves, and because it is quite natural for attraction to occur in those settings. But the fact that I won't call them immoral obviously doesn't mean that such relationships cannot be deeply problematic and that one should think long and hard before getting involved in such.
Adult incest is entirely different. As both parties are adults there actually isn't much of a power imbalance. I would argue that the fact that most of us strongly disapprove of such relationships actually has nothing whatsoever to do with the power imbalance but everything to do with a very severe role conflict. Parenting is inherently about caring for your offspring, bringing them up, guiding them, helping them become their own person. Nurture is incompatible with a sexual relationship. You are supposed to nurture your kids, not lust after them.
Poll
