The coin is certainly very "dirty" in appearance - it could be natural or it could be the result of artificial aging to hide minor flaws/discrepancies.
What concerns me more/most is the "1936" on the reverse at 6 o'clock. On the eBay lot, the numerals give the appearance of tilting up to the NE and coming fairly close to the "A" in "DOLLAR." On a genuine coin, the date is much more level and does not approach "DOLLAR" so closely. This is a red flag for me.
The low resolution of the seller's images make it difficult, for me, to make definitive assertions about other design details that might be off.
If I were a collector seeking out a 1936-D Arkansas for my collection, however, I would move beyond this one - too much potential for disappointment.
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