The reason why dogs always smell their owner’s crotch is because dogs get information by smelling the smell of anal glands, which is a way for them to communicate. Dogs are used to understanding and communicating with their owners in this way.

So often sniffing the owner's crotch is also said to be a friendly behavior, and the owner does not need to be afraid. This proves It wants to be friends with you, and it is also expressing its love for its owner.