I've never had it happen to me personally but I've heard it first hand from some of my (black) friends. I always find it funny when topics are made on GAF about the subject of people not wanting to date people in x minority group (usually involving black people) and the people are called out as being racist and some posters respond "No it's their personal preference", as if excluding an entire group of people from your dating pool based on skin tone is on the same level as "I prefer my steak well done".
The usual argument to support that is, "Well do you like to date fat chicks? No? Well it's the same thing, just personal preference, it's not like you hate fat people."
Honestly my opinion on it is, if you exclude yourself from dating anyone simply based on their race and nothing else, I am 99% sure you're a racist on some level. I have yet to meet one person irl who has that opinion of x race and wasn't prejudice/racist towards that group in some way. One of my ex-friends spouted that shit saying I would never date a black dude while I was in the room, and I was just done. Not to mention she's pretty much terrified of black guys and always thinks they're gonna rob and kill her or something. Whenever we went into the blacker neighborhoods, she would always want me to come with her as I would somehow be able to repel the potential black criminals with my blackness.