I don't see it often, and when I do someone always asks them to not take it. I can think of plenty of applications for it. A versatile support doesn't always have to take something like Exhaust/Flash or Heal/Flash. CV comes up ever minute. I recognize there are a lot of scenarios where it's just not optimal, but it's definitely not a wasted summoner. CV/Exhaust could be really good on a support who buys Mobi boots. Or Smite/CV on a jungler who can run away like Olaf. Shen split push would be super safe with it, and he could ult away instead of flashing if he really needs to, or dash through walls. Not saying CV is the best or anything; just that it's good in its own right.

Clairvoyance does not work in solo queue.

Because exhaust exists.

Wards are WAAAAY more accessible in s3 than they were in s2, and bot lane is far less passive than it used to be. You are putting yourself at a disadvantage by taking a noncombat summoner like CV

Its better with a well coordinated team.

I used to despise the 'take CV man...I can't imagine playing w/out it'...now I miss it...fml

Because you can buy wards to provide everything CV does. You can't buy Exhaust or Flash in the shop.

Mainly because the enemy can SEE CV.
I'd use it otherwise...

CV is for people too stupid to buy wards.

Sightstone