Dodge when the toxic level is over 9000. Don't dodge based on your teamcomp, but if people are already begining to fight and you can tell it will get in the way of the game, dodge. Don't ever dodge based on the champion picks. One game I played in ranked was "zero win potential" with a Garen top, Nidalee mid, and Ashe ADC. I ended up taking Shaco jungle, camping lanes like hell, and we won. Teamcomp only makes a difference in a balanced matchup. Even though Garen is generally considered to be useless in a teamfight, he won his lane hard enough with my help that he was just too big to kill.
Also, I ended up getting a "death timer/movespeed troll" in my game. I looked up his match history and he was on like a 16 game losing streak, playing Janna with ghost/revive. Obviously that's dodge worthy.