I guided whitetails in Northern Alberta and have seen hunters use scents, decoys, etc and some which dont use any. Any difference? Sometimes no, but more than often...yes.
One hunter hunted a spot that had been decent. He ran scent lines and put a decoy on the cutline. That day he saw over 25 DIFFERENT bucks...the most for that stand BY FAR. Every stand he sat in, he had good numbers of bucks...often more than other hunters...
I became a beleiver....and will use scents when I go north this year. I dont think they can hurt, and if anything, they can slow down a moving buck in search of does. Obviously the time of the season, the intensity of the rut, etc, etc can play a bigger role....