Remember when Twitter was the magical service that played a role in the Arab Spring and was going to make the world a better place? Increasingly it is becoming a platform where demented people hurl abuse and bully each other — it's Troll City, packed with idiots, full of sound and fury, but signifying less and less.

CEO Dick Costolo wants to fix this problem (see below). He realizes that the assholes who are taking over Twitter represent a huge threat to the business. "We lose core user after core user," Costolo told his staff in a memo. Users aren't the only issue. What advertiser wants to step into this cesspool?