3 links have been added on this idea.
  1. Unfortunately, some mirrors can make you appear even fatter, leaving you questioning your body image.
    https://www.thesun.co.uk/living/1781923/fuming-woman-accuses-high-street-chain-hm-of-using-curved-mirrors-that-make-customers-look-fatter/

  2. Some clothing retailers reportedly use skinny mirrors in dressing rooms.

  3. “Skinny mirrors” that make you appear skinnier are a thing and can be a confidence booster to some people.