[temp20160423]

a) How do we know these clicks are bad? A sample size of 3 is pretty early to make any conclusions. b) If clicks are not delivering value, advertisers should lower their bids. As Google encourages advertisers to switch to bids set on hitting ROI targets, what really matters to advertisers is that they achieve their targets. If the clicks are "bad" and conversion rates are poor, then bids will be adjusted down, presumably by everyone.

The fact that prices are set by an auction makes the system inherently sustainable unless you think many of the bidders are irrational.

[HereBeBeasties]

Define "sustainable".

Seems like it encourages companies to get in a bidding war against each other in a race to zero profit margins, while Google pockets what could have been their revenue.

[pas]

Profit is already in the ROI target.