Well, its not always a problem, but it COULD be a problem. If you have groceries in your arms, for instance. Or if maybe somebody came over and didn't like dogs and as soon as they got in the door the dogs were bouncing all over them.

A lot of dogs think they are the leader. The Alpha. So lets just say a dog has "separation anxiety". You go to a behaviourist and he/she will say blah blah blah they are separated from their owners and stuff. But the dog is not thinking "where the heck are my owners?", if they think they are the leader, they'll be thinking "where the heck are my kids?!" when you come home they'll be so excited to see you.

I guess its not always a problem, depends on the situation you know? But that was just an example.