I know the question title seems subjective, however the reasoning behind that is because its not an easy question for me to phrase right now. The example i will use is sion and lux, namie.
These champions have knock up, slow and knock up skill shot abilities that cc the target and deal damage. Now if I were in the brush and cast these skills, after the target is damaged they gain vision of me if I am within range,right!? so in Lux's case she would q e then kill you with ult, crowd controlling you with q so that you do not react to her e. In namie's case she would q and then and with the help of the adc chunk you. You see her and lux where the damage is applied. I am not 100% certain about namie as this is something I just recently thought of and I have not had to deal with a namie in that scenario recently to make any comments about it. So I watched a stream where sneaky was q knocked up by sion followed by an e that did not reveal sion's location through out the entire exchange.
If you watch it you will notice that after he landed he was momentary stunned and though he issued a move command. His champion did not move until after the stun duration. During the stun duration he is hit with an e you see the ability exit the brush but sion's location is not given before and after the e reaches sneaky's twitch.
Which leads me to believe that Crowd control can affect a champions vision. Taking that statement to consideration why is nunu's location not given while he slows a team with his ultimate and after he deals damage. His ultimate is a slow so why is it he stays hidden?