Vice (n.): Action that offends the moral standards of the community.
So, it really depends on what community you're talking about.
Vice (N) : A morally repugnant act. A fault or defect.
So it actually depends on which person is judging it.
Which makes the whole thing ridiculous.
Consenting adults have the right to do whatever they want, it's time the laws caught up with this & it's absurd to call it wrong or immoral.