Help Grade My 1850 Seated Dime

I can understand from the pictures I posted some may see what looks like cleaning. All I can say is I'm a amateur when it comes to photographing coins and the lighting is off making it look different than how it looks in hand. I am confident the toning is natural and there hasn't been cleaning. Thank you for all the comments and please forgive the quality of my photos.

From everyone's opinion, I am wondering what is keeping this coin out of the AU grade. This is PCGS grading standards I got from their site and based on this I feel it could grade AU

EF-45 Detail is complete with some high points flat
EF-45+ Detail is complete with a few high points flat. Superior eye appeal.
AU-50 Full detail with friction over most of the surface, slight flatness on high points
AU-50+ Full detail with friction over most of the surface, very slight flatness on high points. Good eye appeal.

I do have the advantage of seeing the coin in hand and unfortunately everyone else has the disadvantage of looking at my bad pictures so I'm taking that into consideration. I would appreciate a little extra help from everyone if they could explain why they gave it the grade they did.

Edit: Here is the link to the standards http://www.pcgs.com/grades/

A couple of comments for feedback:

Sometimes the additional technical merit for the difference between AU and EF comes down to luster as well as pointed out by BH1964. Your coin seems to be missing all signs of luster hence the EF opinions winning majority. I believe your coin misses this luster as this coin has been cleaned, albeit a long time ago as pointed out by zxccc. I suspect a good rag and water wash. The coin has since toned over a hazy shade but there are tell tale signs on the surface of spotting and clustered dark spots especially on the reverse peripherals that make it evident. I suspect most of the collectors and dealers here would consider this a "market acceptable" cleaning meaning, that it has not afflicted the coin to a place that a collector seeking a raw example in the grade level would shun this coin; in fact at the right price, most collectors would buy it for their album.

That's not a die crack, its an old scratch. I can tell you based on Denticle Ruler Measurement, I see what is referred to as DR -1R which narrows it down to handful of possible obverse dies but nothing that is highlighted in the rarity rating scale.

Nice pick up. Are you building a Liberty Seated dime set?