The key is to regularly re-visit these bookmarks and clean them up. For me it means categorizing these saved threads and comments under a specific theme. Maybe I'll write a blog post about it once I've arranged those ideas together. Even if I don't, the act of acting on those bookmarks reduces mental clutter.
Be sure to time-box it though. There's nothing more frustrating than opening up Twitter to review some old bookmarks and then getting distracted in the organization+deletion cycle for 45 mins.