I would disagree with some, and say it is a genre today. Some of the traits would be frequently dance oriented, and rather shallow musically. Beiber, Katy Perry, that whole cadre of divas, and the tween bands of good looking young people playing rather thoughtless, lowest common denominator music inhabit the pop space. If when you see them perform on tv, it's a girl singer surrounded by seven dancers but no band in sight, it's pop music. If the lyrics insult your intelligence, that's a clue. If the chorus is derived by singing the word "whoa" up and down the scale with a severe look on the singer's face as if they're actually saying something, or the intro is a lifeless guitar ostinato written by someone with no imagination, there you are.
There is a very recognizable factory odor to it, very easy to spot.