There's one I've seen that curves vertical. Then, there's a cup that fits over the end. The air pressure causes it to rise, leaving a fairly unobstructed outlet. When the dryer stops, gravity causes the cup to drop, sealing it well from all critters. If I remember, it is paintable. I saw this at HD awhile ago, but don't know if they carry it still or how widespread it is. I first noticed it in a magazine, maybe Popular Electronics.