Sorry brother, those prints are on there to stay. At this point they've been etched into the metal and there is nothing that will remove them.
Great post OP. Textbook example of why toned coins used to be discounted, since there is no way of knowing what is under the tone/oxidation/corrosion. I don't have a problem with people liking pretty, but they should be aware of the risk they are running. Some collectors know this and know the risks, but I would say many don't. A non-toned coin everything is knowable, toned coins they just aren't. Btw did you play around with different dilutions of the dip and different application lengths? A dip can do more harm than good if too long. That I believe is your next step, learning how long or at what strength will work best for each coin. I am not saying I am an expert at this, but I know the real experts are very adept at this and it can make a night and day difference in results. Chris