Why do dogs sniff new dogs for much longer than new humans?

I just realized that when two dogs meet, they'll sniff each other for minutes on end. However, when a dog sniffs a human, it might be for thirty seconds max. It kind of seems like with dogs they're like, "I must smell every single little thing I can about you," but for people it's, "Alright, you're not an axe murderer so you're welcome here."