The two most detrimental personality traits IMHO are lack of personal initiative...
i.e no desire to learn anything beyond what you are taught...And arrogance...confidence is great and important-arrogance is a deadly sin in this business...that's why I think that they should be washed out in groundschool ---I don't want to trust my live to these jokers as a punter...youth and inexperience don't upset me...the two aforementioned traits are what scare me...I've seen many young pilot in Tech log and such with inexperience...but they are clearly showing initiative by posting their questions receiving the guidance graciously...because when the excrement contacts the ventilator blades...those aforementioned types are the first to turn...Yellow and in ab intio schemes unfortunately not all training captains are as good as some I've seen here...a few in particular are amazing in their teaching ability and I'd trust any of their students to take me home with the captain incapacitated in the worst of wx OEI---I definitely can't say that's my general sentiment though...
Airmanship comes not only or even necessarily through experience but also through initiative---barring very, very good training, which clearly is no guarantee that they had good training-too many lazy trainers!!