Are you listening to what they are NOT saying... carefully?
I wasn't watching the signs but after enough of these interactions I am able to draw the following conclusions. I've come to learn three things about people who call you up to "do business with you."
- They need / want you more than you need them.
- When they are overly flattering - it means they are jealous.
- When they tell elaborate tales of past "home runs" you know they're broke.
On the flip side, there are some who are interested in doing business in an earnest way. They tend to have a focused proposal or set of ideas and it allows for you to advance into the "getting to know you phase" sans the B.S.
Finally - avoid taking business development or partnership inquiries from folks who are not established businesses... You know; office, reputation, a well organized website, etc. etc. Otherwise, you're just wasting your time.
My two cents.