Let me tell you a story:

Harold, a small, weaselly man with bad skin, leaves his dingy apartment to go for a walk. His wife stays behind, snoring in a bed with dirty sheets; Harold never loved her, but married her because he had to marry someone. She didn't love him either, but married him because she was too plain to get anyone else; in fact, she's having an affair with the delivery boy from the local grocery store, who drops off wilted vegetables and rank cheese every Thursday, and then has strenuous, grunting sex with her on the ratty living room rug. He has bad teeth and halitosis, but he also has a large and ever-ready penis, so Mavis, Harold's wife, keeps shagging him, though she usually fakes orgasm because nothing much gets her going. Anyway, Harold heads off to work, passing the fat, sour-faced crossing guard Martha en route, and arrives at the door of his company, a boring place that sells badly-manufactured radio parts, where he does a pointless job for an ugly and irritating boss...

Have you had enough of this story yet? Because I have.

It's a surprisingly common mistake in inexperienced writers to produce fiction that's unrelentingly negative. 'There's no fiction without friction', as a writing teacher of mine used to say, and that means putting some conflict in: if Harold skipped down the street and nothing went wrong all day, it would be an uneventful story. But there's such a thing as putting in hostility just to give your characters something to do - and that's not a good idea. It feels forced; without sound justification for the negative feelings you're writing about, then you have characters who are just pissy, which is no fun to read. Ceaseless griping is no substitute for interesting storytelling.

There's another reason why inexperienced writers do this, though, and it has to do with timing. Basically, it's quicker to read a book than to write one. It's possible to read a book in a single session if you have some free hours, but you can't write a book at a sitting. You can only spend a few hours on it at a time, and then you go and do something else. As a result, the mood of the book is not as constant for a writer as for a reader. You can write scene after scene with exactly the same feel without it becoming monotonous for you, because in between these scenes, you do other things. But if other things don't happen between them in the book, the reader gets nothing but the same thing, over and over. Hence, a writer going for a striking mood may decide to get the reader's attention with little character sketches that focus on flaws, without realising that they've accidentally strayed into Hateland, and produced a book where every single character is ugly, incompetent, morally bankrupt, stinky, stupid, or all of the above. It gives the reader a headache to read, but it's perfectly possible that the writer hasn't noticed.

It's not just the monotony that makes this a problem, it's the implausibility. Nothing and nobody is all bad. Some stories have villains who are entirely evil, and while it's crude and not particularly realistic, it can serve a narrative function - but such villains are offset with nice people. It's hard to care about a world where everything is awful; you just don't want to be there, and it also doesn't seem real. Try this:

Harold, leaves his apartment to go for a walk. His wife stays behind, asleep in bed. Harold and Mavis had fun when they first married, but the spark has gone out of things a bit, and while each would like more attention and praise from the other one, they're both too tired to make the first move. Mavis didn't mean to become this kind of woman, but when the grocery boy started flirting with her, even though she hadn't fancied him much to begin with, it was so nice feeling young and desirable again that she ended up flirting back. Now they're having sex when Harold is out, and even though the boy needs to get his teeth straightened and they don't talk much, he seems to want her, which, after years of Harold being so used to her, is too much to resist. Anyway, Harold heads off to work, stopping briefly to say 'good morning' to the crossing guard, Martha, who's been there as long as he can remember. Martha's doctor had told her she needs to lose weight, but she loves to eat too much to listen to him; she has an endless fund of anecdotes she tells in the pub every night and a nickname for every child she shepherds over the road. Harold arrives at the door of his company, where he's done the same job for ten years; it's not exactly stimulating, but he's used to it, and has learned to laugh at the boss's bad jokes because the man is trying to be entertaining and there's no harm in being polite.

It's the same story, but if you cut everyone a bit of slack, not only does it make it more bearable to read, but it gives much more possibilities for character development. In version 1, when Martha discovers that Mavis is sleeping with the delivery boy, her sour nature is obviously going to lead to disapproval, and either blackmail or spitefully telling Harold, who's going to be pissed off with his wife - but as he was pissed off to begin with, we're probably going to end where we've started. Martha as well: she's a sour woman, so discovering an affair is just going to confirm her view of things. Stasis. In version 2, you have a fragile and disillusioned marriage, more subject to change; because Martha is basically an optimist, the discovery is going to surprise her, put her in a conflict where, because she's not a sour cow, she's going to feel empathy for more than one person and have a variety of choices to take. The ending, in short, can be much more interesting, because you haven't trapped yourself in a single emotion in the set-up.

Different readers can swallow different levels of negativity, of course; I can think of some very successful writers who have an extremely negative tone. But as a general principle, it's monotonous to have everything be bad, and it's careless not to check over your work to see if you've fallen into that trap. And if you want your characters to have intense feelings, give them a reason. A good one. There's no point bringing more hatred into this world than it has already, after all, and a bit of compassion is an essential quality if you want to write good characters. If characters feel things without good reason, they'll do things without good reason, and that's not a good story. Cut everyone some slack, and you'll find you have much more room to manoeuvre.