That's great, because their music was simply heavy metal. They've said it so many times over the years. They weren't like Poison or Cinderella. Those bands were glam. TS was simply heavy. Don't let your eyes fool you. :) Trust your ears. ;)
In its turn, not every glam metal band sounds like Poison or Cinderella. These bands were on softer and poppier side of genre, while Cinderella were almost hard/blues-rock at the end of 80s. TS could be considered a band that belongs to a more metallic side of glam metal, though they are still probably not similar enough to the backbone bands of glam metal movement.
Just watched their documentary and it was a good watch. It focuses a lot on their 70's days as a successful cover/underground band, and when they released "Under The Blade" and "You Can't Stop Rock 'n' Roll". It was interesting to see their early days and albums being in focus.
Just discovered "Under the Blade" - this album should be considered a classic in the same vein as Mötley's "Too Fast For Love" (original Leathür mix)! Too bad how the two megahits take so much of the attention, although it's such hits that give bands longevity (and that's good for TS since Dee can deliver a youthful, kickass performance even today).