You may see my suffering,
but you can't feel my happiness.
(By: Dabuan Bodil)
Assessing someone is easy. It's as easy as saying it.
Self-assessment is the hardest thing, because it involves the ego. And very rarely does someone want to judge themselves fairly. Everyone tends to raise their own values, give low value to others. But if you do the opposite, surely you are a wise man.
Like the title in this article, someone is more likely to see the negative side of others, and easily assess. Though there is a saying, "don't judge a book by its cover" which means something like this, "don't judge someone from his clothes or anything that looks from him".
We can very easily see the shortcomings of others, and very rarely give recognition for the advantages of others. Instead we are often more inclined to think what we are doing is a good thing, even though we are aware, and are very aware that what we are doing is wrong.