Someone had a high score so that means they are not toxic?

I have been noticing something odd ever since I dove into the depths of the ranked system. I tend to (and I think we all do) get an odd amount of toxic players that while yes they do trash and shit talk their own teams, seem to do pretty well in lane. Though its what happens after the game that confuses me with how said players are still being clearly toxic yet the other team says something along the lines of "He wasn't toxic he did good in the game" or something along those lines.

This is an over all example of something I have seen a lot and I find it odd that just because a player did well in game means that it acts as a free pass for his/her behavior for some people. This is clearly not a constant issue but it shows its head a lot. What do you think? should players let them off the hook because they played well? Or should they still report against the player for how he acted?

(Just a topic I though of to try out the vote system here on the boards. Now I can provide more information if need be so please feel free to prove me wrong or ask question if I didn't explain something well enough)