When hunting the ground I use local scented vegetation and dirt for cover scent. Early season I also carry a small bottle of earth scent cover scent. When showering during season I use odorless soap as well.
Use to play around with the gimmicks, never seemed to help any.
My experience (Mostly farmland whitetail) shows that as long as you're not too obtrusive, most of the time it takes a combination of two of the deers senses to really spook them. If they scent you, they'll try to see or hear you. If they see you, or your setup doesn't blend in quite well enough, they'll try to scent you. Most of the time if they don't pick you out after a few minutes they let their guard down a bit. The exception IMO is early season does, and of course after the gunfire starts blazing.
To me, wind is the most critical when your entering and exiting an area. Always pay attention to the wind, and set up accordingly when possible, but I've killed around a third of my archery bucks down wind. Two of the closest were 7 and 8 yards, one a young buck in early season from a brush blind, and one a mature 9pt from a 8' tree stand in pre rut.
The young buck was close by down wind of me for a good 5 minutes before I decided to shoot him.
As they say, your mileage may vary, but it works for me.