I consider myself a pretty discerning individual. I think I have the ability to read people with a fair amount of accuracy. I can usually see their motives, how genuine they are, and if they are trying to manipulate a situation for their benefit.
When I enter a room full of people, I can often identify the ones who are genuine, and the ones putting on airs. I can figure out which people I would enjoy hanging out with, and which ones I want to avoid. Being discerning can really pay dividends - mostly because it can keep you out of trouble, and it allows you to be more focused and intentional in building relationships with others.
I guess in this light, discernment (as it pertains to relationships) many times is being able to "see the bad in people." Sounds kinda harsh, but it's the truth. It's a mechanism that allows you to evaluate people - good or bad.
But, as good as I may be at "seeing the bad" sometimes, I can be even better at something very similar, but infinitely more harmful...and that is failing to see the GOOD in things, particularly people.
You see, being able to see "warning signs" and avoiding a situation is a positive thing most of the time. But, when I take this to the extreme and I don't actively look for the good in people, I become callous. It becomes more about self-edification, and less about how I can serve. I become close-minded and judgmental. Intolerant. Unloving. Un-Christlike.
So, I've got to be careful. I know God has given me a "radar" for being able to identify potentially harmful people and situations. But, I also have to realize that I am as flawed as the people I sometimes avoid. And, I have idiosyncrasies that probably turn them off as well.
And, nothing turns people off more than someone who has a "holier than thou" attitude.
God's Word tells believers to be "in the world" but not "of the world." Sometimes I take that to an extreme and try my best to keep myself sheltered from those things that can bring me down. But, God put us here to encourage one another, and ultimately to point people to Him. And, I cannot do that if I step away from those who need to hear about His love for them.
It's something I am working on: Choosing to see the GOOD in people (however difficult that may be).
Because God sees an endless amount of good in each of us.