I've given this a great deal of thought over the past few days. I agree that Charles is largely spared from JA's zinging wit. My impression is that she is trying to present him as a pleasant, well-meaning, patient and good-hearted man...who would have benefited from a better partner.

I think she doesn't want to make Anne's other suitor an object of ridicule. The point is, Charles would have been an acceptable match for the overwhelming majority of women in Anne's time and position (second daughter of a neglectful, spendthrift father who has given his daughter no opportunities). However, she couldn't even consider Charles in light of her ideal. I think JA wants to present Charles as a suitable suitor, so that others who know she has turned him down will wonder...why? I think it would cheapen the value of CW's lingering influence considerably if Anne had only had the opportunity to turn down a silly man...say a Mr. Collins. If I remember, perhaps I'll comment on this some more later in the read.

Interesting, also, the parallels in situation between Charles & Mary and Mr. & Mrs. Bennet. I think Mary would be every bit as annoying as Mrs. Bennet to live with, but Charles (so far!) has remained pleasant and not resorted to bitterness or sarcasm.