I think how each of the character comes across is reliant largely on the sorts of lessons they end up learning. Like, Dash's lessons tend to be the most important, but at the same time they make her the most abrasive for needing them. Her lessons so far this season? 1. don't be shallow (find a pet), and 2. don't let your ego get in the way of your job (MMDW). Needing to learn those basically made her, by necessity, shallow and egocentric,
for those episodes. Keep in mind both of them were fairly unique situations that brought out those traits. She still has a lot of genuinely good qualities, and we do see gleanings of them... just not as much.
Not that that makes you
wrong, per se, I just think it's an interesting piece of perspective. Someone yesterday mentioned a quote that this season is basically dedicate to showing that the characters are jerks who get along when they need to. Now, I disagree with the point in general - we still see a majority of moments where everypony in the cast are being kind and gracious and good - but I understand how the view came about. In Season one we're consistently showing the cast in situations where they can do a lot of good, or at least be normal - sacrificing for their friends, hanging around normally, stuff like that. In this season, a lot of episodes are custom-made situations to bring out the worst in the characters. I can see how this can be offputting, but it doesn't change the fact that even at their worst they sill manage to pull through and be genuinely good people.