Wow, a bit of a confusion of terms going on. To just say "sugars are bad" or "sugars are good" is a pretty broad statement. In essence, every carbohydrate that we eat is composed of, and therefore is processed into some form of sugar. What we want to avoid is processed carbohydrates and unprocessed carbohydrates that have a naturally high glycemic index. These cause large spikes in insulin which has a whole host of effects. While there is a good bit of evidence that these can be beneficial in some instances (namely immediately post-workout:
The Post-Workout Puzzle, especially when combined with the right ratio of protein) continually high insulin levels have been shown to have a pretty direct correlation to many of the "Syndrom-X" diseases of modern civilization, namely heart disease, diabetes and obesity.
This is why I've always been a huge fan of the Crossfit "World-Class Fitness in 100 Words," most-especially the beginning about diet:
"Eat meat and vegetables, nuts and seeds, some fruit, little starch and no sugar. Keep intake to levels that will support exercise but not body fat. "
If you consider "sugar" in that statement to be "highly refined sugars" (i.e. table sugar, High-Fructose Corn Syrup, Corn Syrup, Maple Syrup, Honey, etc.) and "starch" to be high-glycemic index carbohydrates (potatoes, breads and pasta, instant oatmeal, etc.) then you have a pretty simple guide to avoiding a whole host of diet-related problems.
For a bit more info, check out my article about the glycemic index and glycemic load here:
A Short Bit About the Glycemic Index