So, had a bit of an idea while cleaning up my favorites a while back, and now I ended up thinking on it again because of some serious issues with trying to purge tags from my favorites. The idea is for some kind of purge button for favorites, something that could purge either certain tags, or just a button to purge the list fully to allow people to clean up their lists. Mostly came to me because of the limit of 80k favorites people have now, and the fact that, while I am currently purging my list using the "unfavorite" option, so one click removal, that will take at my best estimate a rough 20 hours to do. I plan to do this anyway a bit at a time over the next few weeks, but you can understand my issue if you look at the amount of time. A system to purge favorites would allow users to also get rid of any posts they blacklisted without needing to worry about their favorites being clogged by say, a dozen posts with that tag, that they may have had slip by before they blacklisted it.
Another idea could be that any tag that you blacklist ends up purged from your favorites, which would still allow the same function, but would simply automatically clean up the second issue. So, that's basically the idea, mostly just looking for what other users, or staff might think of something like this.