I noticed these spots on the inside of one of my cat's ears. She's only got them on the one ear, and they don't come off when rubbed, both with my fingers and a wet washcloth. No signs of irritation and I haven't noticed her scratching at that ear.

I think they look like blackheads, but search results mainly show cats getting blackheads on their chins. Similar looking photos of spots in ears have comments suggesting flea dirt (she's an inside cat + I've seen no other signs of fleas) or allergies (no changes to her food).

I'm thinking of trying a bit of vegetable oil to see if that loosens them, but has anyone else seen these kinds of spots on their cats?

Cat tax: