Now, that's lowball. Too worn to guess from these pictures. If I could study it in-hand for a while, I might venture an opinion, but it might simply be too far gone to tell.
This is what I saw. I took it into grading to ANACS and neither of us noticed. It's only when I looked the coin over again that I saw this feature. Obviously I was hoping this was a regular 1928 but appartently I doubt this now. I got the coin returned to me in a flip today. So what do you think now? Would you say this is an "S" mintmark or just some random spot?
Sounds like the consensus is to abandon this one. Strangely, I had a coin I thought looked worse than this one and ANACS slabbed it. I thought it was also a 1928 but they thought 1922 and put in a regular FR 2 holder. Must admit it was one of the worst. I'm still not convinced the date is able to be discerned.
I think I can see the remains of a mintmark, but even in hand, I agree it is nigh impossible to tell for certain.
The problem for this issue, of course, is that you really want to see the lack of a mint mark -- and unfortunately, on this coin, you apparently can't. I guess if ANACS (or any other TPG) can't tell whether it's a P or S issue, they won't slab it. Actually, did they give you a reason why they rejected it?
The reason provided is "Unable to positively determine authenticity. No original surfaces remain due to excessive cleaning, corrosion or other detrimental factors." Sounds like it's something programmed into the computer when given a code, in my case it was a "N9".