I once got curious with one of the family dogs one time while home alone. She was a beautiful black German shepherd with a nice puffy donut. I didn’t get super deep and was too afraid to go much further than a few licks, but it was very warm and a little bit coppery. I’m looking forward to hearing about other people’s experiences, too
As for rimming, when I was a little older, I did rim our yellow lab. It was hotter and tighter than the GSD, and I loved the feeling of my tongue inside him. Didn’t love the taste, but it did feel super intimate and nice that way. Spent most of my time with him sucking him off more than rimming him.