Sense of smell is undoubtedly their greatest defense, but it is a mistake to think, if it were possible, that being scent free is all that matters.I don't buy the color blind theory,or the wive's tale that deer have bad eyesight. It is based on their not picking us up--sometimes--until we make a movement.How many times have you been looking in a direction that you didn't notice a buck until he flicked his ear or tail? Does that mean your eyesight is bad? Of course not. He blended in until his movement gave him away, and it is the same with their seeing us. As for heights in stands, I reguarly climb 35-40 feet when canopy allows, and sometimes as terrain necessitates--downsides of steep ridges, etc.--and still, if he is downwind, eventually he will smell you, unless he is near, which takes your scent over him, before it finally settles. Wherever it settles, you are going to get winded. The higher you hunt, the further the distance that it will be detected, and consequently a little less concentrated. I have noticed that if your scent is less concentrated, sometimes their alert response isn't as alarmed, and they will stomp, blow a time or 2 , and then settle down--gradually, with a degree of caution, yet without flagging and running off. This is where the scent suits are probably the most beneficial---they can dilute scent, but I don't think that they eliminate it altogether. And don't think that being high is an excuse for getting away with unnecesarry movement.Sounds are tough as well. I got busted last fall by a doe, when my pant leg--soft cotton fabric, brushed against my climber's seat--also soft cotton. I could barely hear it myself, so I was shocked when she heard me. Summary--take all of their senses serious, and don't rely on any one method of concealment.