prefer is the keyword there. it's okay to have a preference. but it's still stupid to separate such definitions for 2d porn, because dark skin is a common tag used in many hentai and yaoi doujins and it covers both tan and racial skin color.
also doesn't help that OP put "delicious dark guys" as he may have inadvertently included an invitation to include dark skin in his thread.
either way, this thread is stupid, but if this thread is just for slightly tan or brown guys, than it's at least more productive than the no small top spamming that's going on.