You cannot cover your scent from a deer. You can reduce your scent with proper precautions, but you cannot produce a smell that hides the human smell. A deer's nose is too sensitive to be fooled like that. They can smell the cover and they can smell the human underneath.
When we discuss deer behaviors, it's easy to confuse what a deer can do with what a deer will do.
If I said to you, I have a problem with deer getting into my garden. I was going to put up a 10 foot fence around it, but I know that won't work because a 2 year old buck can clear a 10 foot fence, what would you tell me?
In the case of cover scents, the important thing to know is not whether deer can tell that what they are smelling is a mixture of human scent and cover scent, but rather how do they behave when they encounter such a scent mixture.
I can tell you two things that I know about it. I have personally been blessed to have access to places with huge numbers of deer. And I have spent many many hours photographing and studying deer behaviors . I have personally seen the difference a cover scent can make, and there is an advantage to using one.
Also I can tell you that Dr. Leonard Lee Rue has probably spent more time photographing, studying , and hunting deer than anyone else alive today and he'll be the first to tell you that a hunter that doesn't use cover scent is not taking advantage of a very effective tool.