This paint is labelled and listed as enamel paint, but is in fact water-based, and probably acrylic.
Enamel paint is typically characterised by oil-based paints that dry to leave a hard surface. This paint dries to a soft, PVC-like film, and so was entirely unsuitable for the purpose for which I bought it.
As an acrylic paint (which it essentially is) it's not particularly good either. For model-making work, it is too low in pigment for my liking, requiring two or three thick coats to get acceptable coverage.
Obviously not the fault of the ebay seller in this case, but I would encourage plasti-kote to get their act together.