Anything! From any vendor on the butter, ice cream, custard?

That makes me very sad.
Pretty much, Kurt talked about tests being done on some of the diacetyl substitues where diacetyl was still found. He wouldn't say who the manufacturer was, an I understand his reasoning. Chances are this is not the flavor manufacturers impurity and may be a problem that exists in many flavors from many manufacturers.
The thing that really concerns me is that I'm quite experienced with diacetyl and know that in low amounts the buttery and creamy flavor does not show. For example, nearly every red wine and many white wines have diacetyl although the perception of creamy or butter flavors is often very faint to unnoticeable.
Personally I would like to see the majority of vapers stop vaping these flavors until the manufacturers can start publishing test results that show there is absolutely no diacetyl in their flavorings.
I think people don't realize that there are differences in the way toxins/poisons work in your body. A great many things are only harmful if you have acute exposure above a certain threshold. Ethanol is a great example, you can kill yourself if you drink too much in a single night. But for the most part there are no long term health effects from light to moderate alcohol use. There are other things such as asbestos, heavy metals, diacetyl that have long term health effects. That's why were concerned if there is lead or mercury in our drinking water. Even if it's parts per billion those metals accumulate in your body and are not flushed out, so a lifetime of even minimal exposure is a very dangerous thing.