Does a real estate agent get paid if no contract was signed?

[Mike Schorah]

Hypothetical 

A real estate agent contacts a potential seller (Lead A) for business. Lead A states that she’d like to see if the real estate agent can find her a buyer. If not, then Lead A states that she’d like to put the property on the market.

The stars align and the real estate agent contacts another potential seller (Lead B) who is interested in finding a property first in this tough market. Lead B states that if the real estate agent can find a property matching his criteria, he will use the real estate agent as both a buyer’s agent and a listing agent.

Lead A’s home matches Lead B’s specification in what Lead B wants in a property.

How does the real estate agent get paid in this scenario? Does the real estate agent need to have paperwork signed as a buyer’s agent to get paid or can the real estate agent just match the buyer and seller somehow and get paid? If the real estate agent doesn’t want to sign a buyer’s agency agreement, can the real estate agent still get paid for matching the buyer and seller without a listing agreement with the seller?

For instance, in Pennsylvania