Basically, every guitar solo, keyboard solo and guitar/ keyboard unison that has appeared on a DT album in that order (or, in the order of keys-guitar-unison) since SFAM. They have ALL been redundant and terrible.
edit
Before the flames begin, read what I said carefully. I didn't say every SOLO since SFAM, I said every solo that has come before a unison. Both guitar and keys. Usually terrible.