i'd say perversion is not a "useless" word because it aptly describes behavior of people like say Sandusky.....or the act of two men having sex together...
Of course you would. So let me be clear.
There is no such thing, objectively, as a sexual perversion. All judgments as to whether a given sexual act is "normal" or "perverse" are subjective and arbitrary. If we are to make moral distinctions about sexual acts, and I agree that we should and must, those distinctions must be on some other basis than "normality" or "perversion."
A distinction has already been offered. Some sexual acts occur between consenting adults without any coercion involved. Others occur between adults and minors, or between adults and animals, in which one party is not a consenting adult and/or coercion is involved.
This is not only the basis on which I think we SHOULD make moral distinctions among sexual acts, it is also the basis on which I and others in fact DO make such moral distinctions. We have completely tossed the idea of "perversion" out the window, so that there is no connection at all for us between homosexuality and pederasty. Neither one is something we consider "perverse," but pederasty IS a sex act involving coercion, and THAT is what makes it wrong.
There is no slippery slope here, because we aren't even thinking in terms of "perversion" and there is no recognition on our part that we have made a "perversion" acceptable. There is no such thing, for us, as a "perversion." We are thinking in terms of consent and free choice versus coercion and victimization. Gay sex doesn't victimize people "a little bit" while pederasty victimizes people "a lot." Gay sex doesn't victimize anyone at all (unless it's rape), while pederasty does. The distinction is absolute.