Songs where the predominant riff or melody rips off the feel of an earlier one, and it hits you immediately.
There was a famous case where George Harrison’s "My Sweet Lord was held to have “subconciously plagiarized” from the 1963 Chiffons hit “He’s So Fine.”, which I can hear in retrospect, but not at the time.
(In 1976, Bright Tunes Music sued Harrison because this sounded too much like the 1963 Chiffons hit “He’s So Fine.” Bright Tunes owned the copyright to “He’s So Fine” and received $587,000 when a judge ruled that Harrison “subconsciously plagiarized” the song. Harrison claimed he got the idea for the song from The Edwin Hawkins Singers’ “Oh Happy Day,” not “He’s So Fine.”)
The two that come to mind for me, where it hit me instantly, are
The Strawberries “(Please Baby) Go All The Way” which ripped the opening riff from Free’s “All Right Now”
and
U2’s “Vertigo” (and I’m a big U2 fan, but there’s no denying it) which rips off The Supremes’s “You Keep Me Holding On”
The riff from Come As You Are sounds a lot like the intro riff from The Eighties by Killing Joke. Probably “subconsciously plagiarized”, the riffs are not the same, just similar.
No, Vanilla Ice explicitly said it was supposed to be a completely different riff. It was the fact that it sounded so much like a sample that he got into so much trouble, at least in the press.
After the Troggs got away with basically just writing new lyrics for Louie, Louie and had a hit with it, what was gonna stop anyone else from doing the same thing?