Wow, Simon, way to be a jerk to the two guys playing cellos. (And Howie naturally jumped right in too). I mean, if you didn't love it, say so, but why attack their personalities and career choices? I guess they didn't grovel enough. Simon seems to love it when the acts claim that winning this stupid program is their ultimate goal in life; that they'll be crushed and lose all desire to live if they don't win; etc. It's ridiculous. Everyone knows that only 2 acts go through, and if you don't get the golden buzzer you aren't likely to move on, so kudos to those two guys for not pretending that this show is their only goal in life.
Also, I hate that whole "personality" thing. Yes, you may need a special "spark" to be a star, but one person's opinion on what that is doesn't mean no one else sees any star quality. I guess the cello guys didn't have enough of a sob story, or "We overcame all these difficulties to be here" story. THAT's why Simon thought they were "boring" -- they weren't playing the game properly.