1. Any foreign substance removed from any card is an improvement and need not be mentioned to a buyer.
I don't consider this restoration, such as removing glue residue on the back, but it should at least be pointed out to the buyer. Most buyers IMO are OK with this.
2. Anything added to (like color) a card is fraudulent. Or building up corners. Horrors!
Agreed. How the hell do they rebuild corners? That is FREAKY!
3. Nobody should trim cards. It's not the same card.
Agreed.
4) If ironing out creases is successful, fine.
Hell no!
Sometimes these creases or wrinkles can reappear many months or years down the line (when the card is sitting inside a PSA 8 case!)