1. Make dip: In a bowl, combine blue cheese, mayonnaise, sour cream, vinegar, lemon juice and garlic powder, stirring well. Season with salt and pepper. Cover and chill for 2 hours.
2. Make wings: Preheat oven to 450ºF. Line a large rimmed baking sheet with foil. Place a large cooling rack on top of sheet and mist with cooking spray.
3. In a small pan, combine ketchup, hot sauce, vinegar, mustard, Worcestershire sauce, onion powder, garlic powder, sugar and butter. Cook over low heat, stirring, until well combined and smooth. Pour into a bowl and let cool.
4. Pour 1/4 cup of sauce into a small bowl; cover and set aside. In a large bowl, toss wings with 1/2 cup sauce until coated. Place wings on rack. Roast for 10 minutes, then brush with more sauce. Roast 10 minutes longer; brush with more sauce. Turn wings over, brush with sauce and roast 10 minutes. Brush with more sauce and roast for a final 10 minutes.
5. Remove wings to a large bowl and toss with reserved sauce. Serve with blue cheese dip on the side.