Define what you mean by bad for you.
Yes, they are crap, lol! Mostly sugar & carbs, not much protein or fiber.
Start reading product labels. You want foods that are the least processed. Shop around the edge of the grocery store - fresh meat, veggies, and dairy. Nothing in a box! Minimize your intake of preservatives and high fructose corn syrup. Some canned foods are OK, like beans. For veggies, fresh is best, then frozen, then canned as a last resort.
If you eat anything processed, buy it in the natural foods section. Kashi makes great cereals, snack bars and granola bars.
Yes, what really matters is the total number of calories that you eat in a day, BUT, foods that are high in fiber and protein keep you full longer, so you are less tempted to eat empty calories. Kashi Go Lean Crunch cereal is higher in fiber & protein than raisin bran. It's a great way to start the day.
Sometimes I have a piece of fruit and a glass of skim milk for breakfast, then a Chobani yogurt and some taboule salad for lunch, then a reasonable dinner - veggie, protein, and small portion of carb. I do treat myself to a Hershey's kiss each afternoon at work, and sometimes I buy Edy's slow churned ice cream. It has everything that normal ice cream does, so it tastes good, but it has more air mixed in it, so it's not dense, (110 calories for a serving) as opposed to Ben & Jerry's, which is very dense (290 calories for a serving). Trust me, I looked last night! I also eat veggie stix for a crunchy snack that has less calories than regular chips.
Everyone is talking about protein, but you also need fiber, to, uh, keep things moving in your system, lol! Kashi Go Lean Crunch bars have both fiber & protein. If you are a guy, Clif bars are good. For women, they make Luna bars, which have less calories. Sometimes I have one for lunch with a glass of skim milk.
Also, drink lots of water. It also keeps things moving, and flushes out any junk in your system.
Good luck!