You just know that Mosh probably died a thousand deaths and felt even more self loathing when she realized she had to learn how to use opera glasses from Marie.

Normal people would have just seen it as a learning moment, but I'm sure Mosh freaked out even more because it meant that her "to the manor born" image was taken down a notch at that moment.

Absolutely. To be honest, I really don't understand how someone can be that culturally clueless. Even if Mosh had never been to the opera (and we all know that's the case) prior to her marriage, I don't think it's a stretch at all to assume that she'd seen "Pretty Woman" at some point, given what a global hit that movie was. The opera glasses scene from that movie (along with the escargot scene - "Slippery little suckers") is one of those scenes that I think most people know and certainly demonstrated to many, many people (including me!) the proper use of the glasses. Mosh is just a dolt.