Even the highest quality products can periodically have issues, and that can affect your end products that you sell to your customers. Above all in sublimation, consistency is key to good-looking sublimated products. Sublimation is a combination of time, pressure and temperature. If you lock down those variables, you can lock down consistent results. Keep in mind that the coatings on products can affect these three variables.
Millions upon millions of dollars are invested by the large sublimation coating companies to produce and maintain consistent coated sublimation products. They invest in the cleanliness of their facilities to prevent dust and debris in the coating, and they invest in getting a consistent coating cure. If the coating is not cured correctly, it can affect paper sticking to the material. If the coating gets too soft during the sublimation process while heating up, the paper grain will be imprinted into the glossy coating, which gives you an orange peel or mottling effect to your finished product.
Softer cheap coatings can also wear off in the case of mobile device cases. Further, if there are variances in the thickness of the coating, you will get different color saturations on your finished products.