According to Birmingham English: A Sociolinguistic Study (Steve Thorne, 2003), among UK listeners "Birmingham English in previous academic studies and opinion polls consistently fares as the most disfavoured variety of British English, yet with no satisfying account of the dislike".
For instance, despite the city's cultural and innovative history, its industrial background (as depicted by the arm-and-hammer in Birmingham's coat of arms) has led to a muscular and unintelligent stereotype: a "Brummagem screwdriver" or "Brummie screwdriver" is UK slang for a hammer.