1932 S Washington Quarter, Grade & Authenticity Help

You could send it to ANACS and find out. The 7 Day return policy means nothing if it comes back "Not Genuine" or "Added Mintmark". You will have plenty of time.

After looking at the auction and the MM again, my guess is it's genuine. I would want to be sure though, especially if it was mine!

it looks real to me as well, acetone will not hurt the coin at all if you want to try that to see if the MM falls off but I do not see anything that would make me suspect it has been added. as was said you could always send it to a TPG to get their official opinion on its authenticity and the sellers 7 day return policy means nothing to PayPal, if the coin is deemed to be counterfeit or anything added to make it not as described they will give you a refund, just be sure you can prove you sent it back to the seller by delivery confirmation or even better signature confirmation

No, but it would eliminate the possibility of a glued on MM. If it was soldered on, the acetone won't touch it.

By seam I meant the MM is not coming "from" the field (there a gap between the MM and field). Examining the area around the MM with a 10X loupe under good lighting should help determine this.

You bought from a high positive feedback seller who sells many, many coins and paid a market correct price. That also adds up to a better likelihood of genuine.