Interesting topic but examples are thoroughly out of context. Goes to show that trawling through youtube,  possibly the ultimate global melting pot is not always the best answer. The surrounding culture for most part predicates what is or ins't controversial.

KFC ad with black people in Australia? In Australia racism is institutionalized, there are islands and camps for detaining illegal immigrants, boats with immigrants are allowed to sink rather than being allowed on shore.  Backs represents an extremely marginalized and marginal community. An Australian can go for days or weeks before encountering a black person. The only cotroversy that ad is likely to cause is in the circles of academics and philosophers.

The Clearasil ad for example might be controversial by Pakistani standards, but in the context and market in which it was created it will be seen as cheeky but harmless fun. Challenging parental authority is not only widely accepted, but actively encouraged by everything from television dramas to music videos. It  is unlikely to polarize opinions or carve out a niche in the manner that you are implying.

The toothpaste ad with the black man might be offensive in most countries of the world, except for far eastern countires, where racism against blacks or any other coloured ethnicity including Indians is rampant and common. The ad is only likely to offend the most enlightened and liberal sensibilites in those markets, and represents a rather safe bet.