Displays the price for price 0 - product list

Hi,

If price appear on the listing, it means that you've configured prices for the product. Either on the product itself, or in variants of the product.
You might have done some strange actions which lead to the product having variants with prices still link to it even though you deleted the characteristics from it or something like that.
Try checking the products. If you don't see any price in them, create a mass action with a filter on the column "product_parent_id" equal to the id of the product and an action "display the results". When you process the mass action, it will display you a listing of the variants of that product still in the database. Change the action to delete the elements and that will delete them when you process the mass action, and it should hopefully solve the issue.