It seems to me that feathers for streamers should be selected to provide the desired appearance when wet, not when dry. I don't understand why one would want feathers to be hydrophobic for a fly intended to be fished underwater (except in the limited case of something that is designed to trap air as in some nymph patterns).
Many feathers (e.g., marabou, soft hackles) look limp,clumped, and bedraggled when wet and OUT OF THE WATER, but perform their magic just fine when immersed in water and moving in the currents or being swum by the fisherman. Even rooster hackle, which typically is used for dry flies and is about the most hydrophobic type of feather, serves very well for wings on streamers, because they tend to stay relatively fixed in shape and position. By contrast, rooster hackle makes lousy collars on streamers or wet flies, because it doesn't have the flowing motion in water that soft hackles have.
