What an interesting discussion! I have never before seen the parallel/contrast between Darcy and Charlotte. Since deception is my focus, I just had to chime in.

I agree with BridgetD, Stephanie, and Adrian. It seems Darcy and Charlotte sought marriage in opposite ways. Darcy thought he had to tell everything in order to be honest. He ended up being offensive and not even getting a civil answer. As I wrote in post 44279 above, Lizzy's refusal of him was founded on his first frankly honest statements about her not being handsome enogh to dance with. I think we can all agree that he would have done better to have remained silent.

Charlotte, on the other hand, disliked Mr. Collins and civilly accepted his proposal. I think we also all agree that Mr. Collins would not have had her had she told the whole truth. She is interested in his home and position, not him.

Their situations, however, are not completely parallel. Darcy was in love with Elizabeth. What he criticized was her family's situation and behavior. In her most honest moments, even Lizzy admits that her parents and sisters (except Jane) are sometimes models of silliness and impropriety. Charlotte had no criticisms about Mr. Collins' situation as vicar to Lady Catherine. After marriage, she heartily enters into toadying up to Lady C, in the hopes of further material gain for her family. She objects to the man himself. Could Mr. Collins ever have acquiesced to her view? Impossible!

In short, Darcy was not bound to disclose his true opinion of the Bennet family--especially in the context of his proposal. IMO, this is something he and Lizzy could have discussed at another time, had she accepted him. He could say something like this: "My love, I have been thinking that your younger sisters could benefit from some more refined society. Shall we invite Kitty and Mary with us to London this winter?"