The High Price of the "Free Lunch"

When someone asks you to lunch or dinner, make no mistake there is always a reason and for the most part, it’s not a problem. Depending on the person.
There are three kinds of "Free Lunch"
When someone wants to maintain
When someone wants to pick your brain
When someone wants to pick you pain then use it against you.
I have no problem with the first two.
But who are you having lunch with? (listen to podcast)