I could be wrong, but weren't X-Men, Spiderman and the like always in the trash department of comics? From a European perspective it always seemed so. Sure they have a lot of fans, but they are not really representative of quality comics. (and by trash I mean silly stereotypes and exaggerations are basically implied).
The entire US superhero genre, with some notable exceptions, were in the "trash department of comics". You are right they are not representative of quality comics, but they were and are representative of a large segment of what sells.
Though especially in Europe there's a wider segment of non-superhero comics that sells well (and often outsells Marvel/DC titles by a wide margin), and that is not nearly as sexualised - see my comment elsewhere. But these are very poorly represented in most comic stores in English speaking countries.
The high brow stuff, even in Europe, sold - and sells - in far smaller quantities.
