In my previous work, my boss my horrendous. He didn't know anything about programming, databases or scripts. He often had ridiculous requests that we (two developers trainee) had to refrain.
But he wasn't the one who pissed me off the most.
My colleague, who was supposed to have had the same cursus as me, was as skilled as someone without any knowledge. He spent one year to make a database for a new site, with one table per product type and sub-type, per company and per slider. Today there are 93 tables in a database made for a presentation website. When I proposed to see his work, he refused, saying he knew what he was doing.

Now he's still there, I switched job, but I know he'll get the same diploma as me for this shitty pile of fuming crap, and it pisses me off beyond imagination.