I’m not an expert on affect or children, but it does seem kind of mean. That would be the negative: the youth’s possible feeling of betrayal or a negative effect on the relationship with the kid.
As a kid, it was frustrating to be BSed, but not really to the point of feeling betrayed. There was a big difference in how I felt when someone was just having fun at my expense vs. when they lied to me "for real".
At the same time, if you go too far in the opposite direction, you start banning games in school that not everyone can win, everyone starts getting A's, etc.
Sometimes life sucks, and children should be carefully exposed to this fact, lest they grow up to be useless little doe-eyed innocents.
