Check out the 2011 study: 'Cosmetics as a Feature of the Extended Human Phenotype: Modulation of the Perception of Biologically Important Facial Signals' Basically, people are more likely to trust a woman wearing makeup as it makes her appear more professional and competent and good presentation in general makes you more likable and approachable. Makeup also tends to have a placebo effect on confidence. How well you do your work shouldn't be determined by the amount of effort you put into grooming but you have to keep in mind, sometimes appearances do matter. Maybe check your workplace policy or induction paperwork and if it doesn't specifically outline presentation, you should go to HR.

It's probably for not looking professional or representing the company in a certain way

only in america

That's extremely sexist! Guys aren't expected to wear make up!

Do you work at a strip club?

To all that are saying guys don't have to wear makeup or any such nonsense. You're right they don't, but that is based on the cultural norm of females being the makeup wearers. Instead men have strict rules about our hair and nails. Most jobs require a man to have well kept short hair and nails. Also many jobs require men to be clean shaven which is comparable to makeup as both are a daily routine when required.

Skin bags are wack. I love you.

No. you were written up because you didnt do your make up or your hair. If you work as a massage therapist, or a doctor, or something like that, I dont see a problem.

Find a lawyer, in most states that's actually illegal now

it's called good grooming and proper appearance