A lot of people don't put a lot of thought and effort into finding and cultivating healthy relationships. When you don't strive for something good, then you stand a good chance of getting crap.

When I was still REALLY mentally ill I didn't have a lot of self-esteem, self-respect or self-confidence. That made it really hard for me to have a good relationship with myself - let alone another human being. I ended up with a lot of unhealthy people and none of those relationships worked out very well.

As I've gone along in my recovery, therapy and all that, I've learned about myself a lot more. What do I want, what don't I want, what are my strengths, what are my weaknesses, what do I want to do with my life? As I get to know myself better, I begin to attract (and be attracted to) more balanced, healthy people. My tolerance for jerks disappears, and I am better able to determine the quality of my relationships.

When I just wanted "anyone", I ended up with people who weren't very good for me. As I've learned to look for "someone", I've had much better results.