"Twilight Effect" is when something is given too much hype and credit. The object subject to the "Twilight Effect" is raved about to the point that the amount of praise actually reduces its credibility as well as its quality.
Person1: ONE DIRECTION, MAN.
Person2: WHAT ABOUT IT MAN.
Person1: THEY'RE TOTALLY THIS GENERATION'S BEATLES, MAN.
Person2: MAN, THAT SUCKS. I'M SORT OF DISGUSTED AT HOW PEOPLE THINK THAT. THIS REDUCES ITS CREDIBILITY AS WELL AS ITS QUALITY.
Person1: OH I GET YOU NOW MAN. TWILIGHT EFFECT, MAN.