Benign ads are like ads for toothpaste, Febreeze, or airlines.
Malignant ads are, to give but two examples, for things like gambling and pharmaceuticals. The pharmaceutical business, in particular, was much more widely trusted and had far higher public favorability ratings in the old days when their advertising to the public was severely frowned upon.
Advertisements for vices are generally a huge net negative for society. Cigarettes, alcohol, prostitution/OnlyFans, TikTok and other mind-melting social media and mobile lootbox games... The less we see of them, the healthier society is. In places like the UK, where a huge volume (if not an absolute majority) of advertisements are for vices like sports gambling, you know that things have gone sideways. You can feel it.