Getting a whole black cock in your mouth is a challenge. There are girls obsessed with big cocks, and few can compete with blacks. Her cock is really huge and it seems that many girls excite them, to the point of not even looking for penetration. They are simply satisfied with feeling that huge cock in their mouth. But to be able to introduce a penis of that size requires a deep deep throat. That’s why there are girls who even feel anguish, but not stop it.
You should also differentiate between a blowjob and a fucking mouth, this porn video may be helpful because you will see both. Can you tell them apart?