I recently had an elderly french woman try to correct my english, and even argued with me about a couple of points. She was saying “ago” can only be used at the end of a sentence, adding “er” to a verb always means a person who does that action (cooker, blender, washer…. they can only refer to a person doing cooking, blending, or washing, not a machine), and that we say “mock at” not “to mock someone”.

She was extremely smug and sure of herself.

I’m American, and an english teacher. I don’t think that makes me an expert, but certainly with some knowledge in the area.

On the other hand, this spoke well of my french accent….