Possible Clues:

• Like blank paper
• Without inner surface material
• Wrinkle-free
• Having no inside layer
• Without inside layer (suit); without wrinkles (face)
• Young-looking and plain, at the stationers
• Like some notepaper without wrinkles?
• On the face of it, there isn't a wrinkle
• Stressed, Red backed out, yet to show signs of ageing
• Blank paper could be thus plain