its not the definitive proof you are looking for, but I do recall not too long ago Kristen Stewart was cast in the movie Focus along with Ben Affleck, but then Affleck dropped out and replaced by Will Smith. Stewart then dropped out saying that she didnt think that a romance between she and smith would be believable because of the age difference between the the two of them but Affleck and Smith are only 4 years apart in age.
Speaking of Will Smith his movie Hitch was discussed at some length as well when he was promoting it in the UK he said this
“There’s sort of an accepted myth that if you have two black actors, a male and a female, in the lead of a romantic comedy, that people around the world don’t want to see it. . . . We spend $50-something million making this movie and the studio would think that was tough on their investment. So the idea of a black actor and a white actress comes up—that’ll work around the world, but it’s a problem in the U.S.”
Mainstream hollywood actress will never come out and say that they would refuse to work with black males, unlike in porn where such a position seems to enhance a girls profile. In mainstream many of the studios are corporate owned and scandal is one thing many corporations want to avoid as it is not good got their bottom line.
^This.