[tormeh]

They are very much not meticulous about ROI. The thing to understand about the ad industry is that it's incredibly adversarial. Companies need ads to raise brand awareness and make people aware of new products. So far, so well-aligned. From there on it goes downwards. A company's marketing department is in an adversarial relationship with the rest of the company, aiming to increase the ad budget at all costs. The ad agency often just gets a pot of money from the department, and instructions to spend it all, no matter how unproductive. Because if the marketing department doesn't spend their budget, it might shrink. ROI is often not a consideration at all. And if the marketing department actually do care about ROI, then the ad agency certainly doesn't. Then you have the websites themselves, with their clickfarms and general fraud, and the ad exchanges that empower them.

The whole business is teeming with waste and fraud, but it's a necessary evil so it stays.