Final answer:
A net listing agreement is the type of listing agreement that is illegal in many states due to the potential conflict of interest between a broker's fiduciary responsibility and their profit motive.
Step-by-step explanation:
The type of listing agreement that is illegal in many states due to the potential for conflict of interest between a broker's fiduciary responsibility to the seller and the broker's profit motive is the Net listing. In a net listing agreement, the broker's fee is determined by the amount of profit they can make from selling the property. This creates a conflict of interest as the broker may be motivated to sell the property at a lower price to maximize their own profit.