A song murdered by someone.

Guns and Roses' version of McCartney's Live and Let Die.

I don't know if great songs can ever be murdered by a cover--they survive and the cover just makes one appreciate the artistry of the original artist even more.  I like almost all covers I hear of songs I like, but my least favorite form of covers, categorically speaking, involve opera singers doing operatic covers of popular songs.  I bought, and then only listened once, to Kiri Te Kanawa doing hits from "South Pacific;" it was funny, but not that funny that I wanted to hear it again.

The original version of "Unchained Melody" is so superior that the Righteous Brothers cover shouldn't be played? 

Only the Righteous Brother's version should be played. All hyperbole aside....I think it is the best and others fall short. But its music. People like what they like.

Larry, in general I too dislike operatic covers of popular songs, and like you I don't think I've listened to the couple of Dame Kiri's crossover albums I have more than once or twice. 

There are exceptions, though.  One that I'd particularly recommend would be a 1985 album by Julia Migenes (then known as Julia Migenes-Johnson) entitled "In Love," in which she wonderfully performs a dozen or so classic Broadway show tunes.  Of course, it's not entirely coincidental that in addition to opera she has a substantial background in the theatre.

Speaking of Dame Kiri, one of the most fantastic concerts I've been to was a recital of purely classical material that she gave in New Haven, Connecticut, about three decades ago.  When she was in her element she was certainly a very special talent.

Best regards,
-- Al