Sometimes the sweater was only tenuously associated with the product - there is nothing on the elephant sweater to remind you of Stergene or even of washing clothes. But sometimes, the sweater was essentially an ad for the product - it's a neat trick if you can persuade people to advertise your product for free (and even knit the ad, at their own expense). Here's another promotional sweater, for De Kuyper Cherry Brandy, designed by Wendy Wools. The design on the front of the sweater is the label from the front of a Cherry Brandy bottle, and the stand-up collar has the words "EXTRA FINE" knitted into it, echoing the label around the shoulder of the bottle. Essentially the sweater is meant to look like the bottle. It looks quite opulent, with its rich colour scheme of green, black, red and white with gold lurex.
According to a magazine cutting that I found with the pattern, it wasn't originally planned that it would be published. The sweater first appeared in a TV ad (still viewable on YouTube, see below), and the company subsequently were "inundated with enquiries for the pattern". I wonder how many people actually knitted it and wore it? It does seem to me a bit odd to want to wear such a blatant ad for an alcoholic drink. Did the knitters who asked for the pattern think it was a cool design, or were they committed cherry brandy drinkers?