Guild of Confectioners
It is no friend of Wienrich and Boettcher, as the guild believes as an article of faith that foreigners cannot make chocolate the way Ankh people like it. W&B simply do not understand the peculiarities of the city's tastebuds. In its press release, the Guild explains that Ankh-Morpork people are hearty no-nonsense folk who simply do not want "chocolate" which is stuffed with a potentially poisonous 70% cocoa liquor. They are certainly not like effete la-di-dah foreigners who want real cream stuffed into everything.
In fact, they actually prefer chocolate made from (a glass and a half of?) milk, sugar, suet, hooves, lips, miscellaneous squeezings, rat droppings, plaster, flies, tallow, bits of tree, hair, lint, spiders, and powdered cocoa husks (ingredients listed in order of quantity - or at least, what may well go in to making it, depending on what's in the vats at the time).
According to the food standards of the great chocolate producing centres in Quirm and Borogravia, Ankh-Morpork chocolate is formally classed as "cheese" and only just escapes being labelled as "tile grout" on grounds of colour.
Ankh-Morpork chocolate is to real chocolate what a C.M.O.T. Dibbler sausage is to meat.
This may be a thinly-disguised commentary on what the British confectionery industry is pleased to call chocolate, and the way this optimistic claim is received in European countries with a longer and deeper relationship with the cocoa bean and a corresponding reluctance to cut corners by using cheap and possibly inferior ingredients. Eg, France, Belgium, Switzerland, Austria, Germany, all of whom appear to believe that at the very least, true chocolate should have a 60-70% cocoa butter content. Compare this to the 40% which is legally acceptable in Britain, or (I believe) the 25% which is permissible in the United States. As a matter of fact, even British people brought up on Cadbury's oversweetened and under-cocoa-buttered product will wince at the taste of an American "chocolate" product such as Hershey's, which with the best will in the world tastes like cheap and nasty cooking chocolate. The question arises: is this the same reaction a European, from a more chocolate-literate society, might have to the taste of British chocolate? Yes.
In fact, chocolate is one of the foods most famously prone to potentially lethal adultery in Britain's Victorian and earlier eras. Any half-hearted search can turn up a truly ghastly array of "additives" used in chocolate in Britain, ranging from brick dust to red lead, and even arsenic, which hidden in the sugar content, killed a number of people in Liverpool in 1900.
A blind taste-test conducted for a BBC documentary on chocolate (April 2015) invited a random sampling of people to try three sorts of chocolate. The selection was top-of-the-line Belgian, British-recipe Cadburys, and Hershey's milk chocolate (American). It was interesting that the majority of people tested (being British) rated Cadbury's Milk as being the best of the three. Those who preferred the Belgian were asked further questions - these tended to be people with greater exposure to European chocolate, or who were chocolate connoisseurs. The survey went out of its way to try to find Americans in london so they could get a balanced sample. Interestingly, all but one of the Americans invited to taste the chocolate selection agreed that Hershey's was crap. But pointed out that they all lived in England where far better candy was freely available. A strange fact pointed out is that American chocolate, owing to its different manufacturing method, contains detectable amounts of an organic compound called butyric acid. Which is found in human vomit and explains the strange (to non-Americans) after-taste of Hershey's.