I think I over complicated my question basically all I want to know is does btc travel directly from Buyer to seller so
seller > escrow > (everythings good) seller > buyer
Or does the actual bitcoin travel through the 3rd part
seller > escrow > (everything good) > seller
Neither.
The correct scenario would be: seller > escrow > buyer
The escrow will release the funds only after the buyer has paid and you as the seller have confirmed the payment.
If they do take it to their own pile .. isn't this kind of mixing coins since all on going trades will be in one big pot?
Using it as a mixer could theoretically also work. But nobody will be able to assure you that the btc cannot be traced after all.
If you just want to mix btc I would use a mixing service (e.g. chipmixer) or alternatively the Wasabi wallet with coinjoin.