We were having a little tiff about what makes a cover a cover and not a sample or whatever. Case in point:
It's a cover if it retains the overwhelming majority of the same lyrics and same general spirit of the original song.
It's a sample if someone records part or all of the song for playback during a different song. See Vanilla Ice, "Ice Ice Baby" versus Queen/David Bowie, "Under Pressure" and also MC Hammer, "U Can't Touch This" versus Rick James, "Superfreak."
It's an idiotic ripoff made by talentless hacks if the new song is just a recreation of a familiar hook and handful of words. For example, that recent hip-hop/R&B/what-the-fuck-ever Right Round song is not a cover, nor a sample. It's just garbage.