Yes sugar is bad for you in most cases. Most forms of sugar cause an over-production of insulin which will in turn cause fat storage. I say most forms because
fresh fruit (Fructose) is insulin-indpenendant and does not produce enough of an insulin spike to worry about it. This does not apply to
fruit juices though as they are crap because of added sweetners.
As long as you are not eating 4 or 5 peices of fruit in ONE sitting, you will be fine. PLus most fruit is LOADED with anti-oxidents and fiber and are very healthy for you. It is best to eat fruit alone to allow for proper digestion. Otherwise if you eat it with other foods, you could be subject to gas and bloating.
The only time you want high amounts of sugar is post workout to immedatley replace Glycogen stores.