It does sound like she's just a bit naive rather than malicious. If she's not been exposed to much, and is just spouting what she's been brought up with, maybe a few gentle comments correcting her wouldn't go amiss?
I have friends who would look down their noses at certain things, I just find responding with cheery enthusiasm makes them think twice. E.g.
'Urgh, primark is so nasty, I never shop in there it's just full of chavs and all the clothes are really poorly made. I love getting my clothes from...'
I say:
'Ooh but I loooove primark, so many bargains. That green top I wore last week that you said you liked was a primarni special. And I love a bit of people watching when I'm shopping, you get all sorts in there, it's one of my fave shops' followed by big smile.
If they're a total arsehole they'll carry on deriding what you've just said is your fave shop, if not, they'll say, 'oh right, that green top? Maybe I'll have a look in there next time'. Doesn't always work, but most people are just stuck in their ways and need someone to shake them out of it, they don't mean to be snobs. If they're snobby and proud, that's fine too, but at least they know where you stand and that you're not going to agree with everything they say.