In answer to the OP, DT is taking a cock into the throat. It doesn't have anything to do with taking the whole of a cock, if you only have 2 inches then any WG could probably take cock and balls and it still wouldn't be in her throat, similarly if you're hung like a horse and she only has half of it in, it's still in her throat. Some punters idea of deep-throat seems to be face fucking, which is different.
I often include it in searches and then ask if it's genuine DT as some WGs misrepresent themselves, if it's something I'm really looking for there's no greater frustration than getting into the action and finding she can barely manage a semi deep mouth.