I dunno if these groups would count as a "mainstream" act or "decadent" one, as the context of both words can be widely described in some senses. I'd say some of the stuff from the more modern synthwave/synthpop/darkwave, ect. could maybe fit in this topic. I'd say Male Tears or Night Club, which definitely feels more Italo Disco even than the for mentioned genres and a bit more "fun", perhaps not mainstream in the sense that they are popular selling, chart topping artists, but popular enough in the sense to potentially become mainstream. Their decadent side, I'd say that simply just falls under the counter culture of the material, where it's fashionably dark or decadent, but perhaps not in some deeper context, if you know what I mean.
