I am sure they could smell it but it is a vapor. I can not smell it unless I am right over the unit but there nose is a lot better than ours. IMO human scent is what hits a nerve with deer. It is heated and heat rises so I hope it will be well above the scent stream.

I have only used it this once so I can't answer you question about how long it will last. Thefuel is still 3/4 full and I ran it for about two hours. The scent pad will turnfrom blue to white when it is used up and mine is starting to turn in a few places. Mine came with 3 pads and one bottle of fuel.

SF