The way some, but not all, Latino cultures do. And I'm not surprised that some, or many, Anglos are unfamiliar with this practice. I was reared in South Texas and went to school with a large number of Hispanic students, and this naming convention. Years later, while I was on active duty I served with a Marine of Puerto Rican descent. She explainednthis to me, and further stated that there was some variation in practice, even among those of the same ethnic background.
Ignoring it doesn't necessarily means she's racist, just uneducated. Making fun of the custom? Possibly racist. I don't closely follow Ms. Ingraham as I've always thought her to be an idiot so can't say so for sure.
Actually, in the snip of video I saw it was Mr. diGenova that made the "Latina thing" comment, not Ms. Ingraham.
ETA: This sentence was incomplete and should have read: I was reared in South Texas and went to school with a large number of Hispanic students, and this naming convention was not common..