“走江湖卖假药” can be translated into English as "peddle fake medicines while wandering from place to place" or more idiomatically as "hawk counterfeit drugs as a traveling quack".
"Peddle fake medicines" directly conveys the act of selling fake drugs.
"Wandering from place to place" or "traveling" captures the essence of "走江湖" (wandering the江湖, which refers to the world or society in a traditional Chinese context, often implying a nomadic or itinerant lifestyle).
"Quack" is a colloquial term for someone who pretends to have medical knowledge or skills but is actually unqualified, which aligns with the connotation of selling fake medicines.
Both translations aim to capture the original meaning while adapting it to English idioms and expressions.