Sauron has always been capable of taking varied forms. Personally I'm hoping he turns out the be Halbrand, the wizardzzz dude, the crazy swordzzz, the corrupt looking elf leading the orczzz and Annatar. BTW in the Silmarillion Annatar didn't avoid Galadriel and she couldn't tell he was an imposter, she just got a bad vibe from the dude and he had to put up with her scorn with good grace.
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They should have made the Harfoots speak with a Brummy accent, apart from anything else it would have been a cool nod to Tolkien describing himself as "a Hobbit in all ways but size" if the forebears of the Hobbits sounded like the people of the city Tolkien was raised in.