I have, because of my place here, had the opportunity to do many homespun "experiments" with deer & elk at all times of the year. I have some dozens of deer and elk visible to me right now as I type this.

I can say that scents work...but in my experience only in LARGE quantities will they "cover" the scent of a man. When I say large, I mean very large quantities, say ten or more gallons of sheep, elk, deer, horse or cattle shit mixed in a slurry and left to ferment will create a fairly good masking scent when dumped on a blind.

Another that seems to work well is...HUMAN URINE. For years we have run experiments with false "scrapes" using 4 or so gallons of urnine, stored in jugs and mixed in the ground. Such a "scrape" placed 40 or so yards from a person will so fix a critter's attention that they seem to take little or no notice of the person. Remember, once urine is exposed to the air for a relatively short period of time, the species-specific hormones evaporate and the remaining material is similar to what every other critter eliminates. Regardless, I've seen deer eat the ground permeated by human urine.

As for blue, as long as a man is still, I don't think it matters. For that matter, a deer probably won't notice a man in blue or pink and purple polka dot stockings wearing a flamenco dress and a top hat sucking on a king-sized lollypop as long as he keeps still and doesn't send his wind into them and keeps the sucking sounds to a minimum.

And I do not believe all blue is equal. What we call "Navy Blue", a very dark blue, seems less visible than blue jeans or bright blue especially in dim light of dawn/dusk. And blue as a major terrain feature does not exist in nature except in the sky. That was the point of one study I read a while back.

HOWEVER, add movement, and then is where I believe camoflage {white on snow or other proper camo against a broken outline} does make a difference. Movement is more difficult for critters to identify if the outline of the mover is broken up, for the same reason it is more difficult for us to identify.

One last thing; time of year has a GREAT impact on the deer and elk here, especially deer. This time of year they are dumb as posts. Once the guns go off in the fall? Completely different animals.

BTW: here are some elk. Picture taken from my porch yesterday morning. They are about 100 yards away from the house.