Should You Remove Stains from Trading Cards?

Gone with the Stain - Cleaning Baseball Cards

Is it unethical to get a stain removed from a trading card for resale? What if the grading companies can't detect it the chemicals that are used to remove a stain?

This is the sports card collector's dilemma if they get a card cleaned by "Gone with the Stain." Chris Nerat at the Gavel Chat blog had a great interview and article with the founder of "Gone with the Stain."

According to "Gone with the Stain," they remove gum stains, etc from cards without being detected by the major card grading companies. They say the chemicals they use remove the stain only, do not make the card brittle, and do not have any odor.

I see the point that the cards shouldn't be touched or enhanced in any way especially if you are selling it. Or is it the same as washing/waxing your card before selling it to the car dealer?