Gender racism, I think it does exist?

People say it's not gender racism but instead preferences but I'm wondering is there a very fine line between gender racism vs preferences? This has been on my mind a lot since venturing into the world of online dating. I often see that men will take the time to check every race including "other" but leave off black. Are these exclusions based on preferences or something else? I personally am not attracted to middle eastern men but I would never exclude a middle eastern man in dating preferences because who knows..............he may be just what I'm looking for. I'm just concerned at the alarming rate of profiles that exclude black women and wonder if our society harbors something much deeper towards black women than anyone else. Just a preference you say???? Hmmmmm?????