I've had a question about UV, and for other various fly tying head cements. And that is residual scents. Does UV, Sally's, head cements emit odors that fish detect and then reject our offerings? Obviously we all catch fish with flies that have these materials, but do some fish turn away from certain flies that are "smelly"? I've detected strong odors coming from fly boxes with freshly tied flies, especially those tied with Sally's it seems ,in the past. Such that I never put newly tied flies in a box until they have sat in the open for some time. Always speculated whether odors permeate the materials and leave a scent trail in the water? I've read where some carp anglers will not use head cements because of odor. Also years ago read where some bait anglers wash their hands frequently to keep human scent off their offerings. What say you?