What would an acceptable rate of authenticity mistakes be?

[trambo]

I laugh at the comments who say "zero" is the acceptable tolerable error rate. I can appreciate the sentiment but because it is a human thing, there's no practical way it could ever be zero. I don't like mistakes in the grading obvious or otherwise but to say there is no room for a mistake ever is sort of comical to me.

I think the appropriate answer is as close to zero as possible with the understanding that their opinion is just that, an opinion. Some rely and some don't. No rule says you have to buy or not buy what they're selling....