All listings in a company all belong to the company, not to any agent in that company. Most people don't understand that. What Alan said is true, and it needs to show up on the HUD1 sheet that it was paid. Everything must be disclosed - no under the table payments!!
Many people think that an agent will not try and get the best price for their buyers because it lowers their commission they receive. While true, the difference is pretty small when you get down to the agents money they take home and before any taxes are paid on it. For example with a regular commission these days and an agent making a 60% split with their company $5,000 is price reduction equates to $75 less to the agent.