Like the others have said a clean room is great but it doesn't have anything to do with ingredients. There are also substitutes for diacetyl, acetoin, or acetyl propionyl. A LOT of people think only creamy, buttery, milk, batter etc... flavors contain diketones, but it's not the case...
Let's take for instance - Also expanding on what @JCinFLA said
TFA-Apple Granny Smith, TFA- Juicy Peach, TFA-Boysenberry, TFA-Coconut, CAP-Dragon Fruit, FW-Hazelnut, FW-Hard Candy, FW-Jungle Juice, FW-Kiwi, FW-Mango, TFA-Pumpkin Spice, CAP-Raspberry, FW-Salt Water Taffy, TFA-Huckleberry, or TFA-Watermelon, and the list goes on.... Can you imagine what combinations of juice you can make just from these?
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ALL" of the above contain either diacetyl, acetoin, or acetyl propionyl. This is why you need lab reports. Because it's also in flavors not known to be buttery or creamy. This is why TFA has the new (DX) line free of diketones.
If you kindly ask them for those lab reports, and he or she gets offended, I would move on.