I can see how poor quality coco could cause issues like bug infestation, poor drainage, and excess initial salt content.
But, I don't see how one could blame bland tasting herb on the coco used. I've used 3 different brands of coco, and the herb comes out looking, smelling and tasting the same every time.
Its all about good genetics, regulating and dialing in environment, proper and timely feeding and flushing, and proper post harvest handling. Live that routine day in and day out and your girls will be happy, and you will be smoking great tasting, dank ass herb every day.