The best soap for a hunter to use is a soap with no scent, one that is made with animal fat and is a good cleansing soap. Body oils hold in scent and that's what the deer will smell...cut the oils on your skin, cut the scent.
But beyond all that...the best offense is to just stay upwind...deer have amazing noses...their eyes however, suck. I got a mule deer and her fawn to walk right past me within 4 feet and they never saw me...I was behind a tree, not really hiding, but I was upwind. As she was passing me her tail started flicking and she was nervous, I'm sure she smelled me at the point...I just stayed stick still...
One of my coolest memories...