"How could anyone like--" buddy let me stop you right there. This world holds a vast diversity of opinions, tastes, and preferences. Some of them you will find completely incomprehensible. Some of them you will find disgusting. That's okay. You don't have to make sense of it and you don't have to approve of it. Unless you really do want to embark on a project of understanding, you can just say, with me and Danny Lavery, "Life is a rich tapestry."
If you do want to embark on a project of understanding, I recommend phrases like "can you tell me more about what appeals to you in that?" You don't have to mention that it's baffling or revolting to you. No one's going to feel comfortable sharing their thoughts when they already feel judged. If you really want to know, listen and try to understand. Maybe you still can't, or maybe you'll get to a place of "okay I can kind of see where this appeals to other people." Remember that they don't need your approval to keep liking the thing and you don't need their approval to keep extremely not liking it.
Whatever you do, please, please do not make up your own reasons why people like the thing. "People who are into this must be [something that is definitely inferior to me]." Have you asked? Have you actually listened? Then you don't fucking know. And you probably never will, because people won't feel able to openly express themselves around you.
And listen, sometimes your derogatory opinion might have truth in it, but "those people are different from me and I'm the better one" is a mental habit that nobody needs to be nurturing. It's dangerous. I would rather pull up every seedling of it from my heart than risk letting a wrong one take solid root. That doesn't mean I'm going to warmly embrace preferences that are alien, incomprehensible, or disgusting to me. Even understanding takes work, and it's not always worth it. That's why it's so valuable to just go "huh. Isn't human nature fascinatingly diverse" and move on.
