Wow, I hate the skater dresses so much, especially the Miku one. The fabric looks so cheap (because it's so shiny), I've never seen skater dresses that shiny before in my life. You could argue that shiny = futuristic, but it just looks like a really bad cosplay/cheap Halloween costume where it's shining like the sun.
Usually skater dresses are only subtly shiny or have more of a cotton texture. I feel like shiny + clothes looking like it's painted on your body seems like a bad cosplay, especially if you are an anime fan aware of how their outfits are "supposed" to look/fit. As in it looks weird/wrong compared to a "traditional" cosplay. I think that even if you were a normie that had no clue who Miku or Luka were, it would be strange seeing someone wearing an outfit of an outfit.