SWF is fine, it just means you’re playing with friends.
Chill SWF, try hard SWF, meming SWF are all completely normal.

A “salty SWF” is specifically bad just cause it’s childish, toxic, and can screw over any players they’re matched with same as any salty player.
An example of a salty SWF in one of my games today involved a fully healed Nea unhooking a Dwight in my face, I tried to be nice and go after the Nea and ignore the injured Dwight but he was determined to body block (since the Nea used Borrowed Time on him).
After his body blocking let the Nea get way too much distance I went after him instead. I downed him and then as I was about to hook him the two Nea’s and him all DC’d at the exact same time, leaving the poor Claudette by herself.
It’s basically just being a group of sore losers. As I wise man once said “it’s only game, why you haf to be mad?”