It does totally depend on the beer (of course it does, like so many factors) but I was just thinking of the easiest solution for people who find their extract beer recipes finish too sweet. It doesn't seem to be often offered as a solution though, more frequently you'll hear 'more aeration', 'better attenuating yeast' or 'it's still beer, enjoy it anyway'.
Seems to me a wise use of sugar would solve the problem quite nicely.