If you suspect someone who has posted here is screening a purchase, instead of accusing them, please just say something like this...
"If you are considering purchasing this coin please know that it is usually not possible to authenticate an ancient coin from a photograph. If you are not confident that either the coin is genuine, or the dealer is reputable with expertise and a guarantee, do not buy. In short, either know the coin or know the seller."
I prefer we don't accuse members
of breaking this rule unless we are certain. If someone is repeatedly asking about coins for sale and they don't reasonably explain why they are asking, then maybe they should be reminded of the rule.