Useful advice I heard as a child: don't judge others on how they treat you, judge them on how they treat other people. If the guy you are having a business lun

Useful advice I heard as a child: don't judge others on how they treat you, judge them on how they treat other people. If the guy you are having a business lunch with is extremely nice to you, but an asshole to the waiter, what does that say about how you will be treated after you enter the contract you are discussing? If the girl you just started dating seems super nice, but hates every person around her for one reason or another, what will she treat you like after 5 years?