We boarded to find a CRJ in terrible condition. The bulkhead was threadbare. There were multiple holes in each seatback pocket. The lighting was dirty with stains. The safety placards were all worn down. Delta should have been embarrassed to have ExpressJet flying this airplane under the Delta name....We went into the Sky Priority line and a woman at the counter shouted a question whether we had checked in at the kiosk. We told her no, because we wanted to see if we could make this change. She told us that we had to get in the other line to do that. I asked what the point of Sky Priority was, and she said something about how they don’t really do that.