On the ethics of hypocritical compliments:
Every person has people in his life that exhibit a special and interesting form of "two-facedness." Say, for example, that you're a teenager and your parent is always telling you to stop reading on the couch and mow the lawn, wash the dishes, do manual work outside, do more community service, play more sports, etc. Then you get a reward from a teacher or a high grade, and that parent is the first one to compliment you for it. However, you well know that the reward is the product of all of those moments reading on the couch, and had you spent that time instead on a sports field, you would not have received the award.
In this case, is it more ethical for the strict parent in such a situation to stick to her guns and not compliment her son, acknowledging that she still would have preferred him do the manual labor in place of all that time studying (honest consistency in message), or for the parent to heartily compliment the student and act hypocritically?
I suspect that the parent would not agree with the assumption that the only way for the teenager to achieve high grades was to skip chores and read on the couch.