This is the same philosophy I take with regards to meetings. I'd gladly take a coffee, lunch, or other meeting with anyone who is interested because you never know what may come out of it. Sure, sometimes I'm busy, but there's always time for lunch and coffee. Take meetings, have conversations, let 1,000 flowers bloom or whatever the relevant expression is. But I also state in advance that our conversation is not subject to any non-disclosure agreement, and I explain that we are both free to do with the information whatever we like. If they're not comfortable with that, I explain that the purpose of the meetings is to see what mutual value we can bring each other. That's enough to screen the random meetings.