Have you asked them if it increases the value and if they don’t state being cleaned do they state restored ? I’ve been told cleaning can also remove metal making it more un original also. Experts seem to be able to tell if a coin has been cleaned looking through a loop and always have heard, oh this has been cleaned and if you hadn’t cleaned this coin it would be worth a lot more ? So sounds like if you have a coin of value more research should be done before doing this. Do you have a good coin show in your area like I do. If I have coins or questions, I go to the Long Beach coin show and sell or ask questions about coins I’ve picked up. Also look for chips, I’ve found some real nice ones on occasion.
Torrey