It's often suggested that one should send food back if it's not prepared to the standard/price of the restaurant. But sometimes I just don't feel it's appropriate to the occasion! Extreme example, the night I got engaged I ordered a main with a bunch of shrimp and salmon. The shrimp was bad. About to be engaged, I elected not to mention it (and to remain anon for this post!).
I suspect I would do the same if presented with substandard but edible food if I were a business guest, or a personal guest in many cases, or at some special occasions. Never mind the cost of the restaurant or my "obligation" to allow the restaurant to correct the situation before I post my review on Chowhound ;)
Frankly, I don't think I'd be terribly impressed if a guest of mine made a big fuss about something not being up to standard (unless the shrimp are actually bad, of course!)