To follow up on your response and clarify some: in your dataset, not only do 91.7% of the vendors of 'speed and MDMA' also sell 'Ecstasy'; 76.8% of the vendors of 'Stimulants and Ecstasy' also sell 'MDMA'.
If I understand correctly, this means that vendors were significantly more likely to mention 'Ecstasy' in a product name (or description) if they claimed to be selling 'MDMA' than they were to mention 'MDMA' in a product name/description if they claimed to be selling 'Ecstasy', reinforcing the point that you have just made.
If I understand correctly, this means that vendors were significantly more likely to mention 'Ecstasy' in a product name (or description) if they claimed to be selling 'MDMA' than they were to mention 'MDMA' in a product name/description if they claimed to be selling 'Ecstasy', reinforcing the point that you have just made.