Personally, I don't believe there is, but there is definitely a distinction from each person's own unique perspective of this universe, and so there is a subjectivity to the judgement of what is considered good or bad. I use the metaphor of weeds to explain this. Weeds, as I learned in a horticulture lecture at University, are really just plants growing where they are not wanted. There is nothing inherently wrong or evil with them, but people don't want them growing in their gardens. There could actually be something useful or positive about the plant itself, but it is judged to be negative and pulled or sprayed or taken out in some way.
The mystic Osho has a lovely zen story which exemplifies this aspect of subjectivity/objectivity. In his Osho Transformation tarot, he has the card "Blessings in disguise", with the story of the villager and his misfortunes. First of all, Osho states that the only problem with sadness, desperation, anger, hopelessness, anxiety and misery is that we want to get rid of these emotions, and as fast as possible! But we have to live with them. You cannot escape them - they are the very situations in which life has to integrate and grow. They are basically blessings in disguise. The story of the fortunes and misfortunes of the villager goes like this...
A man had a beautiful horse worth lots of money, so much so that even the emperor wanted to buy him. But the villager refused to sell the horse. It happened one day that the horse had been stolen. The villagers told him how unfortunate he was to have this happen. He laughed and said, wait, let the future come, only say the horse is no longer in its stable. The horse came back after 2 weeks with 12 wild horses, and the villagers were astonished. The man was right, this was fortunate for him! Again the man laughed and said, wait and see. I only know the horse has come back with 12 horses, nothing else. The following week, the man's only son was training one of the wild horses, and he fell, breaking his legs. The villagers again judged that he had bad luck, now his son was a cripple! The man told them not to jump ahead, just wait and see what happens. "My son has only broken his legs, that is all." Two weeks later, the emperor conscripted all the young men in the town into his army, and the villagers said to the man, "You were right, our sons have been taken away and yours still is with you."
So, the lesson is just to state the fact - don't judge or label anything as a curse or blessing, don't interpret, and you will see that everything is beautiful.
Another aspect of negative energy, whether we are talking emotions, experiences or just energy, is that there is always the possibility of transforming it, changing it into its higher vibrational aspect. This is the essence of Alchemy. The alchemist believed it was possible to turn base metals into gold or silver. Tantric practices also work on this principle, of transmuting the poison (negative aspect of the energy) into the nectar (positive aspect of the energy. This is a much harder and more esoteric practice, that does require training in the specific practices, but it can be achieved. On the most basic level, by finding the blessing hidden within the negative experience, this is alchemy in practice, and can be done by anyone.
Sometimes it is not the experience itself that was negative - it may just have happened unexpectedly or we weren't ready for it to happen. This could be true about marriage, relationships, graduating from school, having a baby. All these events should be happy and positive, but if we are not ready for them to happen, they suddenly can become negative experiences.
I don't believe we should negate someone's experience - if they are going through a negative phase, we can't really deny them the right to go through it. It's ok to let them discuss it, feel it, and have compassion for them in experiencing this. The time may not be right for them to hear, 'be positive'. And it may not be for you to say that to them either. All we can really do is look within ourselves, and how we judge our experiences. If we can turn a negative into a positive, even years later, you will feel the lift as the energy entangled in that negative experience is released into a positive feeling. The positivity factor is important, but let's not label all experiences as positive or negative. All the lessons are simply there, and we are all learning them.