No, dancing is not bad in itself. In fact, many different people from various cultures have performed their dances for the Pope himself... including break-dancers. It is very obvious that the Catholic Church does not see dance as a sinful action, but as a beautiful expression of culture and a decent form of entertainment.
However, it is clear that not all dance fits under those two categories of beauty and decency. I'm going to talk about "dirty dancing," "grinding," or the type of dance that goes on in a club, or homecoming dance in high school and even middle school. Why do we dance in such a strange way? I would venture to say that there are two main reasons our generation dances the way it dances:
1. because we are extremely obedient, and 2. because it feels good. The second reason simply supports the first, because we are also very obedient in things that do not feel good at all, such as wearing high heels while our feet almost bleed and plucking eyebrows until they look unnaturally tiny. So the main motivation is obedience.
Whom do we obey, you may want to know? Certainly not our parents. Not our grandparents. Not our religion and probably not our consciences. I think there are a couple different answers. But let's go with Fred. We obey Fred… indirectly, maybe, but we obey him. Fred is a very rich man. He lives in California. He sits in a big office. How did he get rich? He paid beautiful women to wear almost nothing and "dance" with beautiful men on TV. Why would he pay them to do such a thing? Because he wants to improve society, or do something good in the world? No, he paid them to do that because sex sells. Sex sells and we bought it; we bought into it. And that was his plan, because he wants us to buy not just the dance, but the clothes on their bodies, the rings on their fingers, and the make-up on their faces. Some of us buy the accessories, and almost all of us imitate their movements exactly; or at least try to... We obey Fred blindly.
So after obedience, I would argue that our generation "grinds" because it feels good. The Church has nothing against things that feel good. Eating, for example, feels good. But it also nourishes us. Sleeping, as well, has an element of pleasure to it, but it also gives us the energy we need to keep going. You could say that we go on vacation just because we like it, but it also gives us time to spend with our family and rest. So. We dance like that because it feels good, but it also… wait… no… it has nothing else to offer us but pleasure, and a kind of a bad taste in our mouths when we go home and realize that we have just been used (that is if we are brave enough to really think about what happened). That's the problem with pleasure that has no end, no fulfillment, no purpose: if you seek it, in the end it leads you to take advantage of and to use other people's bodies, and your own.
For those reasons, I think it is safe to say that "dirty dancing" is in fact bad, and is indeed sinful. So this is my proposal to my generation: Don't obey Fred. Don't let him make any more money off of you. Don't let your life be led by empty pleasures. Recognize your dignity, and that of those around you. And finally receive the sacraments and pray in order to receive the strength to do so.