Yes, AUDITOR is a Scrabble word!

Letter values in Scrabble US: A 1, U 1, D 2, I 1, T 1, O 1, R 1.

Is it a valid word?

AUDITOR is a valid word in the official Scrabble dictionary (US), the UK Scrabble Dictionary and Words with Friends (ENABLE).

someone who listens attentively
a student who attends a course but does not take it for credit
a qualified accountant who inspects the accounting records and practices of a business or other organization