Here is my seated dollar. It is completely original, but is has a slightly more-distracting problem. Your coin is far superior to mine.
More-accurate pictures. The weird color around the devices is residual luster, not dirt. Sometimes lustrous areas can cause color to pop out even though the worn areas are a flat grey. I often see it on bust halves and seated half dimes. That said, I examined this coin with a loop under a good light, and I was able to find some hairlines consitent with a cleaning pattern. However, given the color of this coin (the main reason why I thought it was original), the hairlines are either indicative of an ancient cleaning, or were a byproduct of the abuse this coin saw in her days. The hairlines were much deeper than I see on cleaned coins. There are a lot of pin scratches, mostly on the right obverse.
I agree. The coin was cleaned at some point. The cleaning was not harsh. No reason the coin should not be in an NGC holder. Nice coin.