i have put in years and years of thought on deer hunting and using scents. here is what i have found out. when using a drag with doe n heat scent: If you get 100 yards away from your stand and put your scent on drag and walk to your stand and hand it on a tree 20 yards away from your stand, you just did it backwards, which i did for years. a deer trails just like a beagle, nose to the ground and from weaker scent to stronger scent. so if you want your scent to be more productive, walk to your stand first, pull out your drag and scent it up and walk 100 or 150 yards away from your stand hitting as many cross trails as possible, then pick it up and walk it back to your stand and hang it where you started.
when hanging scents next to your stand you should hang them 20 yards to the left of your stand and 20 yards to the right when standing with your back to the wind. that way when a buck hits your doe n heat line he will come in but not directly down wind of your scent. the last 4 bucks i killed came into this set, their noses were in the air, lips were curled and it was like they were on a rope. i learned a long time ago that scents are no good if they are up wind of them.
how does this apply to predator hunting: i feel, any wild animal is more comfortable being downwind of what they are looking for, so i have my caller 30 yards to the left of me, the wind at my back, i start calling and the animals hears the sound and starts coming then he hits a scent line of a bobcat, from the bobcat sent i just put by the caller, now he hears it, smells it and if i add a feather on a string by the caller for some movement. there are three things on his mind other than me.
for coyotes i use bobcat scent, for fox i use rabbit scent.
one thing i know for sure from spending many hours in a tree, a big buck is a big buck because he trusts his nose, not many deer will pick you up if your are 30 feet in a tree, but a fox will always pick you us as soon as he gets straight down wind of you and there will be no hesitation, he will turn and go the other way, he will not even look in your direction. i once heard that a person can smell stew cooking on a stovetop as soon as they walk in a room, but a dog can smell and identify all 35 ingredents ( not sure how the measure that) in the stew.