I just made a plum and apple crumble, which was delicious but I was worried it was going to be too sweet because when I was pouring the sugar in straight from the bag, it slipped and I ended up with about 50% more sugar than the recipe called for :-)
In fact, though, it was only just about sweet enough - if I'd put in the amount of sugar the recipe called for it would have been way too tart.
I seem to find this a lot, and I don't have a particularly sweet tooth - I actually like things tarter than many people seem to.
Does it depend on the fruit (if so, which fruits need more sugar?) and/or on whether the fruit was frozen or fresh?