It's not all bad, and you can get rare ingredients, if you don't mind not believing the stories where they came from.

[Plausible deniability works out well, here.]

But I wouldn't believe that any of their potions will have any intended effects. They're just looking to turn a profit, and don't care much about... accuracy.

[She motions.] Up to you, however you wish to deal with this knowledge from here.