We always prepay all rooms wherever possible so that there no hidden surprises and having paid upfront, sometimes months ago, it's all been accounted for and is almost "free".
So we were rather surprised when we were asked to clear our bill in Sankt Goar as we handed our keys in.
I assured the lady we had paid by credit card in July and asked her to check her records. She briefly glanced down, and then with hubby arriving, she smiled and said that we had indeed already coughed.
My feelings on this were that she barely checked anything and certainly did not look it up on the computer. Further, if it was so obvious we had cleared our bill in advance, why not check that before making a claim for payment.
No doubt it was an easy mistake to make but it raised my suspicions...