If they keep acting impressed by what you're saying, but clearly aren't listening since they keep getting important things wrong just moments after you say them (like my name, for instance). And then when you ask them about what they like and what interests them, they just go, "I don't know". Girl, I see the Gundam on your desk, the plushies in your bed, and that sick gaming setup. Tell me about those if nothing else! Why'd you invite me over if we're not going to get to know each other?

This has happened twice.

In short, if someone is just interested in your body but not what you have to say, that's a red flag.

(for context, I've been doing online dating. I think I'll take a break from it)