Outlet installation in metal electrical box
In my opinion, no, this is not "proper".  If your receptacle moves enough when plugging thing in to short out to the box, then you have other problems. The receptacle should be rigidly attached, so that it does not move during normal use.

A mistake I have seen made, is where the unused screw terminals are not tightened down. Depending on the size of the box, this can put the terminal screw quite close to the wall of the box.  Which means it only takes a slight bit of movement, to get the screw to make contact with the wall of the box. 

Another mistake is to carelessly tuck the grounding conductors into the box, so that the bare ground can come into contact with the ungrounded (hot) terminals.

If you do decide to wrap the receptacle in tape, you should not have to worry about higher temperatures.