It’s easy to tell when someone is pretending to listen, but they’re really just waiting for a chance to reply.
Their facial expression is often the giveaway. Sometimes they look a little distant, like they’re lost in thought. Sometimes they look plain impatient, having already disconnected with what the current speaker is saying.
I too am sometimes guilty of preparing my own reply before someone else has had a chance to finish. There’s never a good reason for this, and by writing about it, it’s a helpful reminder-to-self to keep working at it.
Listen to others as you’d like them to listen to you.