Was it Bubblegum? Glam? Hard rock? A singles band in an album era, Sweet played pop melodies throughout the Seventies with such joy and malevolence that the English quartet typically confounded critics in the U.S., where much of their catalog went unreleased: For every glam–tastic American hit like "Ballroom Blitz" there were equally catchy U.K. protopunk smashes like "Teenage Rampage" that...