What are some common signs that a player is toxic?
Nothing is their fault
[slayer-pantheon-popcorn]
Nothing is their fault
[slayer-pantheon-popcorn]
He plays one of them

Abusing pings is a signal to prepare,the full mute on him. Usualy
They spend more time blaming their teammates in text chat for their mistakes than actually playing the game
Ppl are trolling, they don't get any punishments, you flame them, you get banned
Nothing is their fault
[slayer-pantheon-popcorn]
Simple. If they are using the chat more than playing the match, then its clear they are more interested in spamming chat over playing the match, and dodging the incoming rocket that is about to kill them.[slayer-jinx-wink]
Their handlename. If they are a douchebag even from their name, their personality usually is.
Also, "toxic", "or feed" or whatsover are clear benchmarks
In my personal experience, the biggest indicator of a toxic player is that they use "shh" to try and silence people (when they could just as easily mute them and achieve a 10x better effect) or they respond to events in the game that displease them with "zzz".
Every time I have seen someone use one of those two responses, they have, without fail, proven themselves to be toxic.