"How do you recognize intelligence when it manifests itself in a form with which you are unfamiliar?"

This made me think about how the human civilization has been interested in the prospect of finding/meeting a truly 'alien' intelligence, while disregarding the different types of intelligence that might be found in their fellow beings and being resistant in considering such thoughts/concepts as intelligent. If we haven’t yet figured out how to identify with “intelligence when it manifests itself in a form with which you are unfamiliar,” how do we suppose we’ll be able to handle something ‘alien,’ and why are we even so excited about it?