In the last 6 months, I've had to buy a few things that 'normal people' tend to buy (a coffee machine, fuel, ...), for which we didn't already have trusted sellers, and so checked Google.

For fuel, Google results were 90% scams, for coffee machines closer to 75% The scams are fairly elaborate: they clone some legitimate looking sites, then offer prices that are very competitive -- between 50% and 75% of market prices -- that put them on top of SEO. It's only by looking in details at contact information that there are some things that look off (one common thing is that they may encourage bank transfers since there's no buyer protection there, but it's not always the case).

A 75% market rate is not crazy "too good to be true" thing, it's in the realm of what a legitimate business can do, and with the prices of the items being in the 1000s, that means any hooked victim is a good catch. A particular example was a website copying the one for a massive discount appliance store chain in the Netherlands. They had a close domain name, even though the website looked different, so any Google search linked it towards the legitimate business.

You really have to apply a high level of scrutiny, or understand that Google is basically a scam registry.

Not quite the same thing but some non-negligable percentage of ads I see on Facebook are outright scams which purport to be selling musical instruments at a 'markdown'. First guitars supposedly from the Sam Ash bankruptcy sales linking to an obvious fake site and more lately 'free' giveaways of high end Gibson acoustic guitars. When I've reported them I got the feedback that it didn't violate community standards, but my insta account got perma-banned when I posted the original of a song on youtube from 1928 on a thread which started with a cover from 30 years ago. That was considered spam.

I had that reaction as well, but consider: clickbait is such because it takes more work (emotional or logical) to reject it than an ad which is merely not relevant to you. Thus, your (and my) recall of ads is probably biased towards clickbait, and we overestimate its prevalence.

That usually means you tend to visit trash sites. Higher quality sites have higher quality ads. In fact, for the highest quality media, people actually PAY for ads. See things like Vogue September issue or technical shopping magazines, which earn value for being 90% ads. People used to buy local newspapers because of the ads as well.

Ad company says ads are good, water is wet, news at 11.