Level 1 Max Heads are hard to sell, even if it isn't duped (what I doubt) it's just too much trouble going through explaining it to the buyer, I would actually never touch one.
tf2items is a good site, but it isn't 100% reliable. It's a sourceop site, not a Valve one so it doesn't have access all the item histories, only shows item's in public backpacks and in the case the backpack was checked when the item was there. The history shows a tf2wh bot as a first owner, and I don't think that bot preordered the game and got the hat, more like the history got cleared when it went through a series of private backpacks and lost the original id, so it assigned the current ID as original when it surfaced.
It's a well known fact that people when duping items was possible used tf2wh to get rid of the hot items, so a lvl 1 (or 7) Max from there is probably duped. Other level ones with original ID starting with 7 are either Valve created dupes or went missing then reappeared, they can't be checked for 100% sure, but most people will accept them at full price (like this:
http://www.tf2items.com/item/780510800).
Clean Max Heads' original ID starts with 1 or 2 and the history can be tracked back for over a year, before the time people were mass duping items (like this:
http://www.tf2items.com/item/811705859)
If you open outpost and search for Max head trades you'll be surprised how many lvl1 ones you'll see in the first 2 pages.