Sometimes when a player is playing loud and with alot of overdrive (or not!) and you sting a note with alot of attack on the pluck, the note you're playing generates out of tune harmonics in the speaker itself - a resonance - and this sounds BAD! It's annoying and some of Ted's 12's have always suffered from cone cry to some degree.
It really depends on the player. I tend to up-pick and sting and squeeze out a lot of notes...I'm a blues player. Players who have a different style from me may never hear cone cry from a speaker that would generate so much cone cry for a player like me that I would find it unusable.
Lew