I agree, I think it's rude to drop the bomb without backing it up.
but if the deal is as great as it's supposed to be, the seller ought to be able to substantiate that.
I thought I understood the OP to say that the poster did say that $3/case price was at the same location that she stated that she got the $5/case snacks and that the OP has seen them for that price once before. I believe the OP even tried to clarify that in her response on how the normal price is $5/box and that sometimes the stores don't even carry the snacks.
I still think that the poster thought she was being helpful, even though I understand why the OP was angered by her post.
Also, if I fault the poster for anything, it would be for innaccurate information. I'm guessing she saw the snacks cheaper and without making sure that she had the correct and latest info, she posted what she 'knew"...and she was wrong. I don't think she had ill intentions (at least not likely), just misinformation. The OP had a chance to clarify the price and I think can still further clarify the price if she chooses to.