I had to explain to a friend of mine that the reason a girl lashed out at him is not because he wouldn't date her... It's because he felt the need to say that "oh I'm not into asian girls". It's totally cool to have preferences in dating, whether it be a racial preference or whatever, but please don't be a dick about it. I don't think what this guy did was THAT bad, nor do I necessarily think he had malicious intent, but it shows that he's socially oblivious. Like, why mention someone's race when rejecting them? Now they're struck by an unnecessarily racially charged comment on top of being rejected. And if they didn't even ask you out in the first place, that's a triple whammy because even the rejection itself would be unnecessary.

If you aren't attracted to people of X race (or height, nationality, body type, sexuality etc), don't go around telling them you find their race unattractive (or even worse, that that they're undateable losers), when they didn't even ask. If someone asks you out and you reject them for that reason, don't tell them the reason: just say No. No one needs to be told that their race is unappealing to you or anyone else, it's a racist thing to say to someone and completely unnecessary.

Remember, when someone asks you out, they're not asking you if you find their race attractive: they're asking you if you find them - the person - attractive, or whether you're interested in them. (If they do also ask you why you're rejecting them or what you think of their race, then in that case I don't blame you if you tell them)

A lot of people respond to this by saying "oh so I'm not allowed to reject people anymore??" like no, of course you're allowed to reject someone romantically/sexually for literally any reason, but you should reject them with the respect and tact that they deserve. And this includes avoiding saying things like "I'm not interested in you, because people of your type are unattractive". There's zero need to mention anyone's race especially when it's a sensitive topic in many environments. Just say "I'm not interested" and be done with it.

Hearing that the reason someone's not into you is because of a quality that you can't change, or a quality within a sensitive topic, can be quite hurtful. And it shows that you lack tact if you don't recognize this.

As much as I find it strange, I'm not gonna bat an eye if you happen to categorically exclude every single Spanish person from your dating pool or refuse to have sex with anyone with a darker skin tone than yours, but I will call you out if you decide to be rude to them and deliberately make it known to them how you feel about their collective demographic when they didn't even ask about that.