Any marketing agreement or order may contain provisions prohibiting and/or otherwise regulating any one or more or all of the practices listed to the extent that such practices affect, directly or indirectly, the commodity which forms the subject matter of such agreement or order or any product thereof, but only with respect to persons who engage in such practices with the intent of or with the reasonably foreseeable effect of inducing any purchaser to become his or her customer or his or her supplier or of otherwise dealing or trading with him or her or of diverting trade from a competitor, to wit:

(1) Paying rebates, commissions, or unearned discounts;

(2) Giving away or selling below the true cost (which includes all direct and indirect costs incurred to the point of sale plus a reasonable margin of markup for the seller) any of the affected commodities or of any other commodity or product thereof;

(3) Unfairly extending privileges or benefits (pertaining to price, to credit, to the loan, lease or giving away of facilities, equipment or other property or to any other matter or thing) to any customer, supplier, or other person;

(4) Discriminating between customers, or suppliers of like class;

(5) Using the affected or any other commodity or product thereof as a loss leader or using any other device whereby for advertising, promotional, come-on or other purposes such commodity or product is sold below its fair value;

(6) Making or publishing false or misleading advertising. Such regulation may authorize uniform trade practices applicable to all similarly situated handlers and/or other persons. Such regulation shall not prevent any person (a) from selling below cost to liquidate excess inventory which cannot otherwise be moved, or (b) from meeting the equally low legal price of any competitor within any one trading area during any one trading period and the director may define in said marketing agreement or order said trading area and said trading period in accordance with generally accepted industry practices; but in any event the burden of proving that such selling was to meet the equally low legal price of a competitor or to liquidate said excess inventory shall be upon the person who sells below cost as above defined. Any marketing agreement or order may authorize use of any money received and of any persons employed thereunder for legal proceedings, of any type and in the name of any person, directed to enforcement of this or any other law in force in the state of Washington relating to the prevention of unfair trade practices.