I understand where you're coming from. My thing is, if they are going to sell something for money, then the quality of whatever good or service they are selling is reflective of the quality of their business. And the level of respect they have for their consumer. If you bought something from me for $5, you are going to get from me the best $5 of effort I can give (in fact, I struggle a lot because I undercharge and overdeliver). If people complain, they shouldn't be able to complain about the completeness. If I make a lamp for someone and they have an issue with it, it shouldn't be, "lacks a switch".
I don't expect notes to come with the formula for point deduction, but I expect if they are selling me notes, they are descriptive of the flaws. As to people challenging the notes, just make it clear that the grade is the grade and it doesn't get changed because you don't agree. People on Antiques Roadshow can always argue with the appraiser, but it isn't going to make them change the valuation.
If you don't want to give people their money's worth, and you don't want to hear from them, fine. Don't charge them money then.