austen, I like Le Guin too - did you know she wrote a story about a world where people were neither male nor female (as an attempt to explore gender), but later said she was disappointed that, because she used 'he' as default, she felt she'd made a mess of the attempt?
dittany - I'm still thinking of English Lit reading lists. My students come to my subject (medieval lit), and tend to think that there's Chaucer (whom they mainly know as the writer of the Wife of Bath, which they usually think is a proto-feminist text), and there are people who write romances. Neither Chaucer nor Romance is particularly feminist (!), but the feminist criticism on both is strong. It's easy for them to feel as if wonderful modern criticism has found spaces for strong women, and ways to redeem the sexism of the past.
However, to take an example: romances fictionalize the idea that women's chastity is a source of society's honour, and honour for men. Because the idea is fictionalized and negotiated through the text, often humorously, there's space for students to find feminist interpretations.
They don't get to read the didactic literature that is strongly and uncompromisingly misogynistic. They don't get to read medical literature, which consistently defines women as deformed, inferior and inherently unclean. They don't get to read sermons and preaching texts, which often display revulsion towards women.
Because of this (and I've tried to counteract this in my own teaching), they don't realize that these attitudes are so prevalent. And they don't get to trace how similar some of these attitudes are to ones still current in this society. They don't get to find out how ingrained, for example, the idea of women's bodies are dirty is. They don't realize that's a guiding cultural image that has roots in all sorts of literature.
This, I think, makes it possible for them to come to shallow conclusions about the difference between medieval society ('it was sexist, but it was the dark ages! we're different now!) and our own.
Obviously, I've never had the ubiquitous 'do you wax' discussion with my students, but I suspect the answer might be 'sure, it just feels nicer, there's no cultural implications!'. Which is an attitude people develop when they are left ignorant of said cultural implications.
Whew, I do go on! 
Does that make sense? I do teach them about women too, obviously.