Yeah mostly seems to be the pop sensibility that defines it
whether you call it hair/glam/light metal or whatever. Since pop is a dirty word to a lot of hardcore metal fans. But I love pop music so it certainly isn't a dirty word to me and I'd much rather listen to JP or most of the cheesier 80's hair metal groups than most of the more hardcore stuff I've sampled (especially the overly serious stuff with Cookie Monster vox- even at its worst, hair metal still had a sense of fun). And I also liked the song "Dr. Feelgood" by Motley Crue quite a bit as a kid, even using it to make a music video with my friend at summer camp.