It would be fine if they didn't have to bring everyone else down with them! Have you ever wondered why difficult people are so challenging? Is it their innante personality? Something to do with their upbringing? Are they just misunderstood?
My experience is that difficult people are impenetrably hard to deal with for two reasons:
I have a friend who is very difficult and I thought she was clueless to her difficult side. How can you have relationships -multiples, not just one- filled with conflict and not know you are the source? Eventually I realized she knew exactly what she was doing. In fact, she has a lifetime of throwing temper tantrums. It's a learned behaviour but angry rage got her results.
Being moody, angry or disruptive draws attention to you. To restore harmony, other people learn to either leave you alone or give you what you want. It's just easier. However, the long term toll is much greater as it impacts morale.
When I was funny motivational speaker for a Physician Recruitment Healthcare Conference in Boston, there were several sessions on dealing with difficult people... with apologies to doctors!
One of the leadership speakers showed research that suggests that difficult people get better shifts, more pay, and they work with better people. In short, they are getting a lot out of their tirades.
If you let difficult people bring you down, realize that your quality of life is more important than you think. This person's random episodes of misery are affecting your buoyant optimism and ability to remain positive. You must confront and deal with difficult behavior.
Remember when you do address a difficult person, the fear center of their brain will be activated. This sends them directly into a fight or flight response. Thus, they wont be reasonable. It helps to set the stage by listening to them, because everybody wants to be heard.
Relate to how they feel and be kind but firm. Above all, stay calm. Emotions tend to spiral downwards if you both latch onto who is right and who is wrong.
Remember this, conflict means you care. If you didn't have a vested interest you wouldn't even bother. Thus, you both care about the same things and you just need to come to terms with how to get there.
My experience is that difficult people respect when others stand up to them. Some may not even be aware of the behavior that has become habitual for them.
In some cases you may have to agree to disagree. In the case of my friend, when I tell her what bothers me, she refuses to listen and accept responsibility. In some relationships (when you have a choice) you just have to assess if this is worth it. Either you cut your losses and move on, or you consciously decide to pay the price for the sake of the relationship.
Leadership Keynote Speakers Motivational Talk, I Love my Job, it's the People I Can't Stand!