It is a bit dishonest, academically, to point a finger at recording artists guilty of building success on an imitation of what came before. Almost all modern rock owes a debt to early bluesmen and rollicking rollers such as Little Richard, often described as "the architect of Rock 'n' Roll."
Nevertheless, The Monkees get a bad rap as being a pre-packaged Beatles rip-off, a reputation we'll defend them from a bit. Sure, that's what media executives had in mind, but at least they had great songwriters (Neil Diamond), eventually wrote and produced teir own material, gave Jimi Hendrix a spot as their opening act and counted no less than John Lennon as an outspoken fan of their TV show.
Ripping off someone else in music doesn't mean the copycat can't be successful as well.
Vanilla Ice's Ice, Ice Baby was a huge hit, despite copping the bassline from the Queen/David Bowie collaboration Under Pressure.
George Harrison's My Sweet Lord led to a successful lawsuit for sounding a bit too much like The Chiffons' He's So Fine. It didn't stop the song from being a No. 1 hit -- in fact, it scored that honor twice in the U.K. (upon its release and after Harrison died). Harrison also eked out a minor hit about the whole affair titled This Song.
Born this Way by Lady Gaga showed that she could not only recycle shtick Madonna trotted out 20 years ago, but could craft an aural echo of Vogue.