If you want a 'decent' guy... get used to the idea that you're going to be spending more time alone... getting to know who you are as you sort through the 'riff raff' in your pursuit of what you want.
Maybe you're so afraid of being alone that you desperately cling to these men you know aren't any good? You might want to question your motives in past relationships. Try to see if there were signs all along and you simply didn't want to see them.
That's why people say you have to be happy with yourself before you can hope to find a decent person... because desperation and poor self-esteem will blind you to how people really are, and you're left to repeat the same mistakes over and over again.
Stop blaming others for YOUR choices... and be HONEST with yourself. If you lie to yourself, you'll never learn how to be happy with yourself... and thus never attract someone who could genuinely care about you.
"The weakest soul, knowing its own weakness, and believing this truth that strength can only be developed by effort and practice, will, thus believing, at once begin to exert itself, and, adding effort to effort, patience to patience, and strength to strength, will never cease to develop, and will at last grow divinely strong."
- James Allen