I was in F on a CR9 flight yesterday with an ESA next to me and one behind me. The one next to me was some kind of ugly frufru dog that stared at me the entire flight and panted. The dog stunk horribly. I took a picture, but for privacy reasons I won't post it here. Then licked my arm when I put it on the armrest. The owner made no attempt to reposition the dog. Then the dog started growling at the dog behind us. It prompted me to complain to DL for the first time in probably 400 flights. I realize DL is hamstrung by the twits in the ACAA that allow this chaos, but ultimately I paid DL for the "experience". I don't see any reason ESAs can't be required to be put in a carrier. That would solve most of the traveling public's concerns. I bet other countries laugh at the whole US ESA debacle...
PS: The dog's owner behind me (in Y+) was drunk, and he kept yelling at the FAs as they went by to get him another drink and more cheese-its. And they did. He was talking loudly enough behind me I heard him say he was moving. Later I saw the guy pushing the (40-50lb) dog around in a wheelchair swerving all over the place. Tried to get a video, but he stopped at the first bar.