You feel your talent in life is being able to make instantaneous, inerrant judgments about the strengths and weaknesses of any individual?
I am going to have to agree with Professor X that you are probably flattering yourself with this super power. While I agree that it is certainly possible to 'read' people over the course of a brief encounter, particularly with regards to stressful situations and only as far as certain traits or inconsistencies are concerned, being able to accurately judge the spectrum of one's character as far as evaluating their 'strengths and weaknesses' is something that would take a little more time.
The only person I've seen who can do this is House... and he isn't real.
As far as your actual topic is concerned: yes, I can see the silver lining on the piles of shit I see every day just as I notice the occasional smudges on the otherwise pristine characters of people whom I also happen across.
Of course, I still classify people as douchebags based on single tidbits of information because, shit, I see a lot of people over the course of my day and I need some way to filter out the rabble. While I wouldn't consider these pricks to be Satan incarnate, if they happen to personify any particular trait I find distasteful I happily reserve the right to just consider them a piece of shit - or, at the very least, not give a crap about them - and move along rather than dirty myself rummaging around piles of coal hunting for potential diamonds.
I think most people operate the same way. Very few people, I would think, genuinely believe that any one person is "all bad" or "infallible". However, there will always be traits that ultimately color one's perception of an individual, whether it is the many small ones that allow one to conclude the person is an all-around good fella or even a single horrible one that forces one to believe that the person is a scumbag.
I'm sure more than a few of the Catholic kiddie diddlers did some good work in between pressuring underaged boys into blowing them, but I certainly wouldn't be shedding any tears if they took a bullet to the face. Likewise, I would still consider Mother Teresa a good lady if I found out she enjoyed the occasional shoplifting binge.