According to generally accepted practices, personnel who work in services sector, are required to be conservatively well groomed with make-up applied using pastel tones. Our current cabin uniform is also composed of muted tones with no accents of red or dark pink. Accordingly, the use by cabin crew of lipstick or nail polish in these colors impairs the visual integrity of the intended look. The facial and hand appearance of cabin crew are especially important, since the service procedures make passengers especially aware of these grooming aspects. As a result, THY believes that a more natural presence builds better communication by presenting a more gentle demeanor. Consequently, Turkish Airlines has adopted a policy that requires service personnel to use personal grooming products that are in a more muted color palate.
http://www.turkishairlines.com/en-int/corporate/press-room/press-releases/22716/turkish-airlines-official-statement#.UYovkvHIIVo.email