In 2010 a customer had purchased Easton carbon bars, I think they were EC90 or something. Rode them for a year, crashed, and rode them for another 6 months before they cracked and he cracked his collar bone. No marks on the bar from the original crash, just a scuffed up right brake lever. The bar broke at that very lever, so the obvious crack was not visible to the naked eye. We inspected the bar, he did as well, but it turned out a visual inspection was not good enough.
DON'T BUY USED CARBON PARTS.