A Mary-Anne

I would like to know the meaning of the saying "she is a Mary-Anne"

Without more context, I'm going to guess that it is a reference to Mary Ann from the TV show Gilligan's Island. Her sweet, naive, fresh-faced country girl is often contrasted with Ginger, the glamourous Hollywood starlet.

Never tell me! That sweet, fresh-faced girl just got arrested for drug possession They've been publishing photos of her in which she looks like hell
SS

I hope I look that good at the age of 69! I'm not familiar with the expression "Never tell me!" - any info on that?

Is "a Mary Anne" a synonym for "a Mary Sue"? (VSD)

I had to look that up. A term from fan fiction for an overly idealized character or one has unrealistic skills or traits for no other reason than to advance the story.
If anyone is a Mary Sue on Gilligan's Island, it's the Professor - he knows everything. What university program teaches both coconut radio engineering and bamboo bicycle mechanics?