Its very simple I've been doing it for over 50 years bear hunting and any other animal hunted from a permanent stand.......for weeks before the hunt put clothing that the person has worn with what ever insect repellent that is going to be used during the hunt.....I put out every couple days and any time it rains different cloths and insect repellant.....
Most bears will just walk in to a bait and don't even care your sitting there..... others will look and sniff then come in......