First, I separate out cracked and broken posts.
For the rest, I do a couple heated ultrasonic cleaning cycles in a 50/50 simple green & water solution.
If any look bad after that, I separate those out and just keep the good ones. I then rinse them off with warm water, then let them air dry.
It's basically just a few minutes of effort. I usually end up keeping a little more than half, and replacing the rest with new posts. Thankfully, the translucent posts don't end up looking all that different from original posts. Solid color posts usually do just because the new ones aren't color matched. White Gottlieb posts, especially (I avoid using new ones if possible since the are certainly not white).