Deer either can't smell the Thermacell, or don't associate it with a threat. I've shot a few deer now that have walked nearly underneath my stand while using the thermacell. Prior to the thermacell, I was using a spray called No Stinkin' Bugs. They have a couple formulas...one is unscented, and the other has a "fall" cover scent with it. The stuff came in a pretty small can, and was pretty expensive, but worked fairly well as a repellent and had very little odor.