I need to know if the following statement is true and the source. 
"Women who wear make-up earn up to 30% more than women who are equally
capable and don't wear it."

OK, let's say that that women who wear make-up earn 30% more than
those who don't (and are equally capable), and credit Max Factor as
the source ( which is not correct).

The statement cannot be substantiated.  The "equally capable" proviso
cannot be demonstrated, so we don't know which women we are comparing.
It can be assumed that more women who are employed wear make-up than
those who are not employed, which by itself could justify the "earn
30% more" statement.
But that has nothing to do with the implication of the statement: 
"Girl, if you  just wear make-up, you can earn a lot more."
And if that "girl" fell for the implication, I would have to question
her "equally capable" qualification.  If she were, she would have
already been astute enough to know how to enhance her "professional
image".

Dear myoarin-ga,
Thank you for your comment and confirmation.  I didn't think that the
statement could be substantiated either.
Sincerely,
imagemaker-ga

Well, image maker, I did locate, actually, the study that many sites
refer to when they claim that women who wear make-up earn more.
However, this is a development of the claim made in the original
study, which is actually different: people who seem more confident and
pretty would earn more.

However, there is some criticism on this theory. One is claiming, for
example, that it is possible - with money - to hire an image
consultant, or even go to a better hair dresser. That is, people are
first hired into top positions and then become "beautiful" (not to
mention that some very expensive suits look better on any of us than
something bought at your local thrift shop).

Another claims that the more beautiful people develop social skills
that help them step up the ladder quicklier, earlier, in life.

Yes, indeed, to politicalguru's last sentence.  Within the last week,
I read that prettier toddlers and young children are treated better by
everyone (not just their parents, but by them, too).
This naturally is favorable to their own selfesteem and confidence,
which can result in their being seen as leaders.  Not all rise to this
role, but some do.
Similar thing occurs with boys and men who are taller.  There are some
statistics that show that taller men earn more.

Thanks politicalguru!  I might be interested in seeing the study that
you mentioned.  I'll let you know.

imagemaker