The orcs of mordor had probably never seen elves and not heard of hobbits .... like Faramir's companions they probably thought anything they didn't recognize would be elves...... too soft footed and subtle for men......
And I think it is clera in nature and inclination hobbits are much closer to men than elves...
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“But Finrod walks with Finarfin his father beneath the trees in Eldamar.”
Christopher Tolkien, Requiescat in pace
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