When puppies chase their tails, it’s like babies grabbing their toes. It’s a way to explore their bodies. It’s not usually a problem unless dogs do it all the time. See if you can distract your pup. If they would rather chase their tail than eat or go for a walk, it’s a problem. You may need to talk to your vet about training or medication.
Dogs like to sniff each other’s bottoms, but it’s different when they nose up to someone’s crotch! It’s not bad manners, according to your dog. Dogs can get a lot of information about other dogs by sniffing around down there. They probably get the same info by sniffing people, too. If your dog’s nosiness bothers you — or the people they sniff! — obedience training may help.
It’s common for dogs to scoot or drag their bottoms across the ground after doing their business — especially if their stool is loose. But if a dog scoots a lot all day, see your vet. Scooting can mean impacted anal glands, which you should get your vet to treat. It could also come from having a tapeworm.