I think it is always unethical to represent value or rarity, or probably anything else for that matter in an auction or sale when you know the information is wrong. If you know the information is wrong, don't include it. The tougher question is, if you know the values/rarities in published guides are seriously off, do you have an ethical duty to tell someone that, even if you say nothing about those value/rarities in your description? I think it's always best to be honest, personally.

Michael Siskin