Since he's a single man and cousin-marrying was all the rage, you'd expect the Bennets to be stoked about this visit. But they're not.
First, he's a clergyman—a pastor in the Church of England. Not nearly as sexy as being in the military.
Second, Mr. Collins has the inheritance rights to the Bennets' house because of this tricky little piece of law called "entail," and Mrs. Bennet is worried that he'll kick everybody out of it as soon as Mr. Bennet dies.
She also blames him for the entail because he's basically an idiot—which he is. But the entail still isn't his fault.
At dinner, he and Mrs. Bennet have a teeth-achingly awful conversation about how her daughters are so beautiful that he's sure they're going to be married soon; they'd better, or he's going to make them all destitute when he kicks them out of their house; but—wink, wink—he's prepared to admire them.
Mr. Collins thinks he's being vague, but everybody knows he's decided he will marry one of the Bennet girls.
Everyone immediately says "Not it."
Mr. Collins praises everything. A lot. And then apologizes a lot for praising the wrong things, like assuming that one of the girls helped cook.
Duh, Mr. Collins, they have servants.
Mrs. Bennet's opinion of Mr. Collins is rapidly improving.