Proverbs 15:3 The eyes of the Lord are everywhere, viewing the evil and the good.
Obviously the eyes of G-d is but a metaphor to describe how G-d "sees the world". Within this verse we can learn something about the eyes of man.
Contrary to the "eyes" of G-d, the eyes of man cannot see both the bad and the good and remain impartial. A man that sees a bad thing will be very negatively affected, mentally emotionally and physically.
From being negatively affected to making more poor choices and going even further down that negative road is not hard to picture.
That is why one should Guard Ones Eyes and keep a distance from negative images.
By avoiding this negative influence one betters his chances in all aspects of life.
It is a difficult thing to do. In my opinion it is more difficult for some types than for others. How can one do this? The Torah has the perfect prescription:
Talmud Kidushin 30b. Even so did the Holy One, blessed be He, speak unto Israel: ‘My children! I created the Evil Desire, but I [also] created the Torah, as its antidote; if you occupy yourselves with the Torah, you will not be delivered into his hand."