One can easily consider the important factors of music without highlighting someone's "bad" performances. It creates more negativity than the contrary.
I never said it was the best way, I'm only suggesting that, perhaps, we could try to take the best from the worst, if you will? There's no negativity spare when negativity is intended; an artist should be able admit their faults and we shouldn't feel ashamed for agreeing with them or pointing them out in the first place; I mean, um, when I foul up I don't mind being told so, I don't mind it being mocked even. Maybe I'm hasty in trying to defend views contrary to your own and for that I'm sorry, but...just consider that the negativity may not actually exist for some...
I never said you said it was the best way. I'm just saying that, um, perhaps we can focus on learning from positive things, instead of searching for holes in others' playing? No one is saying artists shouldn't admit to their faults, we all have faults, we're only human after all. Well, I don't know. I guess some people get pleasure out of watching others fall. Makes us feel superior and in control, hmm? Basic human nature.
It's starting to seem as if we're no longer talking about our all-time worst concert listening experiences, but about more general faults in people's playing. My feelings about talking about those are quite different than about talking about the worst ever musical disaster you've witnessed.
I think it can be useful and helpful to recognize and talk about what isn't good about various performances if we think there are problems with them, either technically or interpretively, or both. It's a way of learning what to do or not to do, and it is also, IMO, one of the best ways of refining listening skills and musical taste and intuition.
For example, it was invaluable to me when I was younger and much more likely to idolize performers to have people with more experience point out various problems with my idols' playing (even if they were sometimes rather brutal about it). And now, even if I'm past having those kind of youthful infatuations with performers, I think it is still healthy for me to hear negative opinions about performers and performances I admire. If nothing else, it reminds me that there are a gazillion points of view, and mine is only mine. Better, it seems to warn me about getting all lazy and comfy and self-satisfied about what I think matters in music - not that I always heed the warning, but I'm glad it is there.