One thing I can't stand is when author take the easy way out. Don't get me wrong. I've done this, too, and I hate myself for it.
You know what I mean. When motivation is glossed over, or a character is faced with an impossible situation, but wait, suddenly he's the master of a little known Asian fighting art that is the only thing that will save.
For me, even an unbelievable story needs to seem believable. And that means not taking the easy road. Not copping out. It's something I learned from my late teacher/mentor/friend Bill Relling. He would never let any of his students get away with easy outs. He would question us and question us until we gave in.
"Why does he find the knife under the car?"
"Because it was there."
"Not a good answer. Why?"
A pause. "Because...he needs it?"
He nods. "Yeah. But?"
Another pause. "But just because...he needs it doesn't mean it should be there."
A smile now. "So...?"
"So I'll change it."
Admittedly, that's a pretty lame example, but essentially it illustrates what I mean. (I would have been a horrible critic back in the old Greek days...Deus Ex Machina? Pah-lease!)
If a character needs a ray-gun to solve the plot, make obtaining one believable within the world of the story. If a detective needs info about a suspect, don't have an ex-lover conveniently sitting at a bar ready to spill the beans. Make the detective work. Make the ex-lover lie. Make the lies tell the true.
DON'T MAKE IT EASY!! But as a corollary, DON'T MAKE IT COMPLICATED FOR COMPLICATED SAKE.
Make it believable. Make it real for the world you are writing about. Make it gripping. Put up obstacles that are really obstacles. Make your characters work. Make 'em think. Make 'em make mistakes. And even the good guys get hurt now and then.
Just don't cop out.