We waiters knew it already, but know it has been proved scientifically: waitress with makeup receive more tips and the amount is higher, but only from male clients. They have done the research with 247 guests (186 males and 98 females). They have been served by two waitresses. One day they used make up and another day they didn't . Follow the link to read the exact method and results. The percentage of customers who gave tips increases when the waitress had makeup. (by the male as female guests, but only the increase by male clients seems to be significant. I have to check it out with some people more clever than this crazy waiter...) Also the amount increases (given by male guests). Read the whole research here.
So we conclude in the words of the researchers:
These results have some practical implication for females employees in bar or restaurant. They confirm the effect of servers’ physical attractiveness on the amount of tips earned especially for waitresses. It would be interesting for women’s restaurant employees to use facial makeup to enhance their physical attractiveness and then, in return, to enhance their incomes especially in bars or restaurant where men used to go.
So ladies: now you know what you have to do girls tomorrow!