Some of the most common issues for which I get training calls are separation anxiety, leash reactivity, and home defensiveness. In many of those cases, I can trace the root cause of the behavior back to the owners.
Dogs are masters at reading our body language and emotions. So, it is no wonder that these behaviors, which can be extremely frustrating to an owner, become part of a cycle of learning.
Check out this article from NatGeo for more.