I have looked and will continue to look as this isn't the article. But here's one in Australia where passengers showed up and denied boarding because the ship was oversold. I recently read an article where this happened, I'm almost positive, in Europe and I believe there were 11 passengers who had flown in from other places...and there they stood. We were in the GTY position and I'd rarely been more relieved than when we got assigned cabins. So, yes, it can happen.