] And, why would she be willing to accept his word on face value - simply because his manners were all politeness and he was so agreeable? I would think that the old art (as described by Caroline Bingley) of making another look bad so as to make yourself appear superior would be something Elizabeth could recognize immediately.
I like to consider myself a reasonably intelligent woman, and I can confess to having made a leap of logic (or faith?) very similar to Lizzy's, here. From her point of view, as I see it:
" Darcy was rude and hateful at the assembly and insulted me directly.
While I was caring for my ill sister, we had some very bizarre conversations, and he was rude to me again (I maintain that she thought of the "don't you want to dance a reel" bit as a direct insult).
The whole last day I was at Netherfield, he was uncivil, he sat with me for better than half an hour once without speaking.
He stares at me, and eavesdrops on my conversations. Why? He must find me really abhorrent.
Well, (nyah) I find him pretty darned abhorrent too, so there.
But wait, Bingley likes him, and Jane keeps making excuses for him.
So it isn't satisfying to talk to my usual confidante, Jane, about how horridly proud and arrogant Mr. Darcy is. Well, then, I'll keep it to myself.
Hey, wait -- this nice looking charming guy, who seems to like me a lot -- he hates Darcy too! Wow, a kindred spirit! I can vent about the arrogant Mr. D, and there is someone in the world in total sympathy with me. I mean, besides my mom. He's even giving me more information to confirm that I'm right about not liking this guy."
So, I agree that she jumped on Wickham's story a little too eagerly, and vented her own spleen about Darcy in a way that was not appropriate, especially with a stranger, but I can sympathize with her feelings. I see it as a natural consequence of her discomfort around Darcy, her eagerness to chalk up his strange attention to her as evidence of his character flaws, and a desire to have her own feelings and opinion confirmed.