Enamelled versus painted:
A piece that shows "stretching" of applied colours normally means the application has been done when still hot. Then the blowing (with or without mould) causes different size "blobs", with the largest / thinnest being around the wider parts of the shape.
I would not think even the most patient of workers would easily achieve the same effect by painting the "blobs". In any case painted work would usually be done 'cold', after the main shaping, but perhaps fired on later.