I think the real question is not do scent blocking sprays and clothing work, but are your chances EXACTLY THE SAME if a) you smell like a big, hot heaping pile of human crap, or b) have taken reasonable precautions to reduce your scent?
Nothing beats the sound advice of playing the wind and learning all you can about how it carries scent. But I would have a hard time believing that reducing your scent doesn't matter at all. Perhaps the stronger the odor or the more foreign odor a deer smells, the more alarmed or on a alert they might be (or just completely spooked). Whichever path you take to GET INTO the woods or your stand, etc, most of the time you aren't going to be able to look back and SEE every inch you walked on the way in. What if a deer crosses your path...one that you MIGHT get a shot at sooner or later that day...and picks up a mild human scent? Or what if they pick up a very strong human scent plus other foreign scents? I just don't know if I believe that their reaction would be the SAME either way.