They cut the second to last corner. They pull up so much dirt on the track that it's like driving on ice. Skill 95%, Aggression 100%. GT3s and GT4s. The AI themselves seem unaffected by the dirt.
I also would like to point out that, even before the AI dirty everything up, some tracks just have way too much **** on them when they're green. I've been trying to practice on historic Spielberg (no chicane), and it's like a dust storm came through. In some parts, there isn't even a clean line.