Are you talking about the stuff that comes in a big jar that you soak in warm water? The stuff that's got a dehydrated mix of greens, veggies, dandelions, worms, and grasshoppers in it?
Because if that's what you're talking about, that stuff is actually really good for dragons and most will switch to it right away because it's colorful and has many textures. Plus it's still a variety of most of the same things you'd give them fresh anyway. My dragon loves that stuff. Soak it, sprinkle some calcium on it, and there ya go.
As for the dry processed pelleted diet.. That stuffs not as good and you'll have a heck of a time getting any dragon that wasn't raised on it to even touch it. It doesn't even look like food to a dragon. Plus it's processed. Like chicken mcnuggets. Ew.