I both like it, and don't like it. Rashford used to be livid with Fellaini in particular, throwing his arms in the air, and shouting to the air. It was behaviour like that which led a poster on here to make a post about needing to burst his bubble. That's an example of when I don't like it.
An example of when I do like it, was evident in the most recent El Classico. Griezmann failed to make a pass which met Messi's expectation. As Messi turned around to look Griezmann in the eye and tell him he should've been released the ball quicker, Griezmann was smiling. Griezmann seeing that Messi was unhappy, placed his hand on Messi's back to defuse the situation, and tried to continue moving and Messi called him to give him further instructions. By the end, Griezmann wasn't smiling.
One of my favourite examples of it has to be Alexis Sanchez at Arsenal. I'm not saying he was always like this, as he wasn't. I forget which game, but there was a game where he was directing his teammates for at least 35 minutes. Gesturing with his hands which player his teammate should pass too, when to slow the rhythm of the game down, when to accelerate, instructing players to stay wide, and later instructing them to come closer. He was a real conductor.
I remember Carrick giving instructions to Tyler Blackett concerning his positioning, and in less than 2 minutes later, Blackett blocked a cross. In preseason, Wan Bisakka was benefiting from the council of Pogba. Pogba was telling Wan Bisakka which positions to take up in offensive areas.
It's not something that we as fans are privy too, but I'd love to know which United players specifically are sore losers in the dressing room. I remember it being reported that Thierry Henry would be livid in training if teammates weren't up to par, and was practically unapproachable in the dressing room after a defeat. Ideally the atmosphere would be so uncomfortable that it would serve as extra motivation to not be in that atmosphere again. Apparently there was a game which United lost the 2nd leg, but qualified overall. The players were celebrating in the dressing room, until Zlatan walked in and started throwing things around in frustration. The celebrations then stopped. Rashford once said he can't relate to certain players from Man Utd that look unaffected in the dressing room after a defeat.