They are quite the opposite. It's why I like them so much. I enjoy neutrality but the warmth they give makes them easy on vocals and great on acoustic. I found them fun to listen to although they sounded mushy in comparison to more neutral headphones like the HD800 which had a much deeper soundstage too
I used to own a DT880. It's tonally very beautiful and has a lush treble, but not very dynamic compared to, say, Beyerdynamic's more expensive headphones like the T1, or compared to the Audeze or Senn HD800. When you say it's "mushy" it sounds to me like you are describing how it compresses dynamics somewhat.
Personally, I don't think the HD800 is neutral. It's thin. But maybe I'm just partial to my LCD 2 rev. 2.