One personality type that can quickly be spotted is The Vain Academic. This is a person who boasts about their high impact publications, frequently drops names of their famous friends, and speaks disdainfully of others (particularly students). If you're familiar with Harry Potter, in my mind I usually think of this person as Professor Slughorn.
Sometimes, a vain person can be appeased with flattery and encouragement. You can quietly smile and nod your head at the right times, gently fanning their ego while occasionally making intelligent quips of your own so they still consider you a respectable peer. You do not dominate the conversation.
However, Vain Academics are people you need to tread carefully around, particularly as a junior person. Their egos are extremely fragile; much of their self-esteem is wrapped up in their accolades and connections. If they perceive any hint of false flattery or mocking behavior, the relationship will sour quickly. Furthermore, if you over-elevate them, they will then view you in a contemptuous way, which becomes difficult to recover from.
On the other hand, The Vain Academic also seeks approval from all, so even if you commit a gaffe (which you surely will), you can probably recover from it. Especially if you are a peer or superior, they will want you in their fan club.
Remember that old advice, "At dinner, you can judge a person by how they treat the waiter"? It's the same with academics; in particular, how they treat students. This is probably the biggest tip off.
