Learn English – word to describe someone who does nice things for others, only to make themselves look or feel good

I just cannot resist mentioning the term nitpicker here.

a person given to harsh judgments and to finding faults

"a tiresome nitpicker who seems to think that I can't do anything right"

reference http://www.merriam-webster.com/thesaurus/nitpicker

"Slacker" has the sense of someone who doesn't do work until compelled to (e.g. By the boss's presence). Where a "shirker" would like to avoid the work entirely, a slacker is perfectly capable of doing something but chooses not to at the moment. Here's one of the definitions from Urban Dictionary: "someone who is very lazy, doesn't do their work until the last minute, and frankly, enjoys it." This doesn't catch exactly what you want, but I don't think you'll find something more specific to the boss coming into the room.