Which leg should a dog lift when peeing? Why

A dog may lift its left hind leg or right hind leg when peeing. This depends on the dog's habits. The reason why dogs raise their legs to pee is because the scent traces can be moved to the height of other dogs' noses, which not only allows the scent to be sprayed in eye-catching places, but also makes it easy for other dogs to smell it, telling other dogs where the scent information is located.
The smell of dog urine is also a by-product of being able to identify odors, which can easily allow other dogs to recognize the smell of this dog, and the odor information will affect the dog's decision whether to approach the other dog.