I was serving a couple from Japan and started by introduction in Japanese.  To my surprise this offended the lady (but not the man).  In my thinking I thought that speaking Japanese to Japanese guests would make them feel more comfortable.  This Lady seemed to have a very strong personality.  I began from then on talking to them in English.  Being slightly peeved at the notion that I offended her, I didn’t bother slowing down to see if she could understand.  Later on forgetting that she preferred that I speak in English I asked “oishii desu ka?”  She then corrected me saying that I should say that and should have said”ikaga desu ga?”,  I thanked her for the correction and  asked the reasoning for the difference.  She mentioned to me that by asking oishii des ka you are implying your food is not always good.  I went on with the evening trying to win her over although difficult I think I did ok.  Later on a table next to her the Japanese gentlemen told me in a hushed voice “she is a witch, and not to worry you are doing a great job”  he had heard everything the lady had said to me that evening and thought she had mistreated me.  The funny thing about it is I saw her come in again the following night.  Thank god I didn’t get her!  I must say I love my job but you can’t win them all.