Well said Bowtie. To condense to one sentence, IMHO it raises a red flag about the seller, and is something I wouldn't do. Use common sense. He knows they don't work. If even one was working he would get a better price so would have posted that. To me, the untested raises a buyers hopes, as has been said. If he knows something he should post it.
Bottom line: if it's sold untested, you can be sure SOMEBODY has tested it. Especially when a simple test would raise the price.

Is he any worse than many? No. But in the interest of full disclosure if I see a red flag I post it.