Since you agree with me that there exist "disgusting and slimy ads out there", and I agree with you that there's some that merely facilitate information, perhaps the more interesting question is "what's the ratio?"

I firmly believe that the vast majority of ads out there are unarguably manipulative: feigning time-sensitivity to pressure people into purchasing, availing themselves of psychological tricks with color and attraction to retain eyeballs, purchasing praise and endorsements and passing it off as sincerity, etc.

The ratio is probably at whatever gets the most money from the advertiser, or as close to they know how to be.

So perhaps the real question should be what incentives we can create to tilt that ratio towards useful information and away from slimy things?

In my country coupon (or whatever else) in 1-15% range probably means that original price was raised and afterwards discount applied to simulate "sale". This is also heavily influenced by the fact that most of products are imported and bought by dollars/euro and currency is fluctuating every day by several percents. Discount higher than 15% probably means that the product itself is not what I think - it is either refurbished or damaged or without warranty or expired or the market is lying to me somewhere or it is another product altogether.

Any rare cases of honest discounts are statistically below threshold and can be safely dismissed - just threat all sales as a lie and you'll be almost safe, that's what marketers taught me.

That's be fine if I just went to a site and searched for coupons, when I needed an appliance. Same result, cheaper and nicer for everybody. Its the pervasive ad noise that's at issue.