Today's Special

Among all the honest trade, some goods are intentionally left hidden behind the counter. In order to acces the 'special' goods some merchants have to offer, one has to have knowledge of what is called 'today's special'. To some it might be confusing to learn that this special is not just a single item, but a whole set of terms used to talk to merchants if one wants to acquire that are deemed illegal.
In order to learn about the codewords required, one has to first acquire a twisted glass. This item distorts the users view of whatever is in front of them. Crafty merchants and their associates have found ways to write in a way that the glass would reveal secrets included in their advertisements.
For the uninitiated, there are some more obvious clues left, like a smiling wolf, which siginifies that there are some illegal items on sale.
The wolf is so commonly used that every inhabitant of Nell's trade nation knows what it means, including the law enforcement. However, shops that use this symbol most often only sell illegal but ultimately non dangerous items, which is why they are tolerated. The main draw of these shops is that in there, someone might be willing to teach today's special to a customer, for a price.
After having ensured that the student has no affiliation to a rivaling merchant or the government, the lessons can begin. The first lessons start with how to hold the twisted glass in order to realign the text in front of them to form new symbols. This itself is a harder task than one might imagine as the angle has to be very specific. The second lessons includes what the symbols mean. They range from simple classifications, such as 'weapon', 'armor' or 'spell' but might include whole descriptions and sometimes even the prices for the items one could acquire.