On a serious note: Yukari is probably showing Satori images of some pretty horrifying images such as wars and mass-slaughters she was probably a witness to in her long life.
Poor Satori looking into the mind of one of the great old ones will probably give her nightmares for weeks. It could be worse she could be seeing Yuuka's thoughts.
Come to think of it I think Satori probably would hate to see my thoughts as well but there's no way they'll be as perverted as Yukari's.