I would describe Slade as 70's Glam.. the same as T rex, Gary Glitter, Sweet, Bowie etc although all those mentioned have slightly different angles on the 'Glam' genre. Slade were mostly a 'rock' band whereas T rex were more leaning toward 'Hippy' and Bowie.. well he did whatever he felt like but all well within the Glam/glitter genre.
Irrespective of his crimes and penchant for prepubescent girls, I love the music of Gary Glitter. The overall sound of his work is spectacular and a good friend of mine saw him perform (a concert) before his downfall and claims it was the best concert he has ever been to, which includes Led Zepplin, Pink Floyd and Queen as some of his attendences.
Now 80's hair metal glam... There is only one winner - Motley Crue! But the 80's spawned some spectacular glam acts such as Twisted sister, Poison, Guns n Roses, Cinderella, La Guns, Pretty Boy Floyd and Faster Pussycat to name but a few.