. . since that's my main use for them. Blue block, which has proven quite durable.

They get cleaned with hot coffee in the morning.
They get cleaned with beer during the day.
they get cleaned with red wine in the evening.

But, when they are as bad as you describe, I spray the with Agent Orange, which is extremely quick and extremely effective.

No, not that Agent Orange - it's my name for powerful citrus peel based cleaners (which I use a lot). I keep a spray bottle of a strong solution for cleaning CDs and glasses, and it is extremely effective.

I learned about it many years ago from new hand cleaning potions for after doing auto mechanic work - the only thing that is effective for that. As most auto mechanics can attest - you wash your hands well with strong soap, and then peel an orange, and the orange peels are dirty. Someone finally monetized that.