It's important, I think, for a writer of fiction to maintain an awareness of the pace and shape of the book as he's writing it. That is, he should be making an object, not chattering.
The characters you refer to as predatory and unsavory are useful. They're the ones who make a novel into a thriller. They're active, and most of the common virtues, the signs of a good person, are not.
I do try not to spend much time reading in the suspense genre.
