Anyone who's lived through the Myspace age understands angles. Back then profile pics where only an arms length away...OK they still are, but selfy-aficionados have the innate ability to aim low. Not with their expectations, rather with their camera. With arms outstretched, a little downward nod of the head. and let's not forget that ducky face. Hey presto, you have a 2003 Myspace profile picture ready to decline all those friend request from awful bands you've never heard of.
On the flip side, if you ever wanted to portray someone with a pig nose and a little extra "something", angling the camera upwards from bellow is a great way to take unflattering self portraits. This Korean girl in the video above especially understands the importance of angles. Observe how she magically transforms from space alien to glimmering k-pop superstar with just the simple placement of the camera. If there's anything practical to be gained by this it's that you don't want people seeing up your nose.
Just be aware...this method unfortunately does not work in all situations.