My personal run with scent control & cover has been an evolution of trial and error. When I first started hunting elk in my teens the big thing was using "elk in estrus" scent. Thinking that smelling like an estrus cow along with calls may lure a bull into bow range. I abandoned this approach when it didn't bear fruit, plus I was tired of smelling like urine (I'm sure smelling like dounuts, coffee, and doritos didn't help either). Playing the wind seemed to be the best approach back then.
In my early 20's, I found out that playing the wind was a must. Especially since I usually smelled like a stinky bar after a night out with the boys before the big hunt.
In my later 20's I was introduced to scent control. I say scent control because there is truely no way one can eliminate ones scent. My cousin, who is an excellent whitetail hunter, showed me some basic practices to keep your scent to the minimum possible. His whitetail hunting tactics modeled old trapper techniques of wearing rubber boots and gloves when dispersing attractants, and utilizing what was available on the market (carbon suits and sprays) to further reduce human scent in the treestand. The carbon suit was actually first employed by the military for chemical/biological warfare (keeping the bad stuff out) then by special forces personel in fooling a guard dogs nose (keeping the bad stuff in). Obviously the later use was noticed by the hunting market, and ScentLoc was born (among others).
As I employed these tactics I began to notice I was getting much closer to game. The carbon suits, rubber boots, and scent elimination sprays seemed to do the job when I was in a still hunting situation. When a spot and stalk was needed, I never seen total proof of scent control, but I was also still playing the wind. Experience I'm sure played a part in this too, as my hunting prowess grew with time in the field. I did find, as stated in this discussion, the ScentLoc suit I had on didn't breath very well, and I found myself quite lathered up by the time I reached my quary after a hard hike.
I have recently added a somewhat new technology to my arsenal of scent control with the X-scent silver weave found in some undergarmets (The X-scent weave takes odors from your body and nutralizes them, instaed of absorbing them like carbon garments). My wife bought me a pair of Medalist thermal underwear with the X-scent silver weave incorperated in the garmet for Christmas of '03'. I was highly skeptical of this "scent nutralization" garment, but they were warm and comfortable. I put them to the test on an '04' caribou hunt in Alaska. I spent 5 days out on the tundra, and I never smelled myself until I took off the garmets. They impressed me enough that it is now a permanent part of my hunting appearal.
The X-scent undergarment is a much better choice for the long hikes of spot and stock elk hunting as a base layer under my lightweight 3-D camoflage top layer. The breathable, sweat wicking, cotton garmet is great during the early season on warm September days. As the weather get colder, I add the ScentLoc suit as a middle layer.
I use the above scent control measures along with hunters soap, baking soda to wash my gear in, and scent control sprays. Once again, I do not believe that my scent is completely eliminated, but reduced enough to help keep from spooking game.
Playing the wind is always a must, and a tried and true practice as old as hunting itself. I just like using as much as there is out there to help give me an edge. I hope that my long winded post will help some decide to give scent control a try.