How should we deal with unknown incompetency?

I already touched on the so-called „Dunning-Kruger“-effect: People’s actual competency is negatively correlated with their perceived skills.

The ideal counterparts might be people who either know that they are competent (?) or do not know, yet (?).

One can also cope with the few who are cognizant about their incompetency (?) – but: How should we deal with the incompetent colleague or even boss who does not know it (?)? 

Well, unfortunately there is no magic bullet but sometimes it does help if you just say how you feel about it and what you need for a constructive next step – stay healthy and confident … 🙂