My guess is that no reputable TPG will slab a coin with a thick layer of dirt, grease, paint, or any other obvious contaminant. If the coin has any value, you certainly wouldn't want to seal it up in a slab together with the dirt.
Sometimes you have to clean a coin, at least to the extent of soaking it in some water and rinsing off the crud. If you post a picture you'll probably get a lot of advice....
I guess it depends how much their is. Like jaobler said, pictures would help. I've seen coins that were slabbed my NGC and others that had some dirt on it, mainly around the letters or numbers.
Disclaimer: While a tremendous amount of effort goes into ensuring the accuracy of the information contained in this site, Coin Community assumes no liability for errors. Copyright 2005 - 2026 Coin Community Family- all rights reserved worldwide. Use of any images or content on this website without prior written permission of Coin Community or the original lender is strictly prohibited. Contact Us | Advertise Here | Privacy Policy / Terms of Use