come on. who can really blame rory for not believing jess when he said he hadn't gotten into a fight with dean? is that such a far-fetched idea? i understand rory's reluctantness to take jess at his word on this. i'm convinced that the number one thing on rory's mind when she brought jess to dinner at the grandparents' house was "oh, God, i hope this doesn't turn out like it did when i brought dean over." so when jess shows up with a black eye and signs seem to point to jess and dean fighting, i can't blame rory for making the assumption she made.
however, i can also understand jess's point of view. jess has been through a lot of criticism since he moved to stars hollow, so when he works hard to avoid dean and keep away from trouble where dean is concerned only to be blamed for something with dean that didn't even happen, that would obviously be a huge frustration. he probably feels like the work he puts in to "straightening up" for rory is in vain because she won't take him at his word. that's frustrating. i've been through it with my own parents.
i thought it was quite comical to watch emily be sugary-sweet to jess, knowing she couldn't stand the thought of him by himself, let alone him being with her perfect granddaughter. she did a good job, and it was nice of her to put on that face to minimize the drama because Lord knows there was enough of it at that dinner. but it was so fake it was almost annoying. but i suppose that's emily gilmore for you.