I personally prefer and have only fished with undressed treble hooks for at least the last 25 years. However, in the last 2 weeks I've had several anglers ask me for dressed treble hooks. So, I whipped out the vice and made a few this morning. I still have some odds and ends to work on if I decide to make some with dressing, but what are your thoughts on dressings?
From personal observation I've seen that trout will almost never hit a spinner if there is a little bit of algae (or aquatic weed) on the hook. If you are fishing a stream that has a good bit of algae, it won't take long for the dressing on the treble hook to get dirty and look and smell like algae. Therefore, I never use spinners with any dressing on the treble hook. I fish my spinners naked.