I have witnessed 2 amazing concerts by Barenboim. I can't comment on your experiences becasue I was nto there, and you can't comment on mine, because you were also not there. I respect your opinions and your views, but you cannot say that he systematically and consistently comes out on stage without practicing, you just don't know the circumstances.
I think the thing to always remember is that he is a great musician. OK, you may not like his playing, or conducting, or musical ideas, but he is a special person.
Do you not think that he has achived any greatness? I would rather take a risk and pay to see him, and ok, I may hear a messy performance, but I may also hear something really profound, like the openign of the slow mvt of the Hammerklavier last week. I would rather hear just one moment like that, than be bored by a pianist who is "clean" all the time.