I once heard a piece of music on the car radio and definitely put it down as a Mozart composition. It was announced as a work by Saliery composed some years before Mozart fame. The point is, musicians have been pinching idea's from each other since forever with the odd pop song based on classical works from 100+ years ago.
I'm not really a loop guy but think using loops is no more criminal than using letters of the alphabet to string sentences together, its just a different art form. It's repetition that never moves off the spot that drives me nuts.