I work in ads for the airline space, I'm on the engineering side so I can't give great financial numbers offhand, but we usually do trial runs on just subsets of routes an airline offers, and for every customer so far the increased revenue on those routes heavily outweighed the new ad spend. Of course you can make bad ads, just like you're saying. We have departments dedicated to that though, I myself couldn't tell you too much about making a good ad that a few SEO blog posts wouldn't cover better.
But it can be formulaic to a degree. If you're an airline, give us some of your metrics and we can get a pretty good estimate of your ad performance at different levels. Got a SaaS product, video game, new snack? We're useless, but there's likely some company of analysts out there who have you covered.
I'm sure it's extremely variable by market though. Air travel has huuuge volume and lots of customers from every tech-proficiency level. I often get YouTube ads for B2B SaaS services and other extremely targeted business things, and I wonder who is signing a 20mm contract that started from a YouTube ad?? Maybe some other commenter will tell me it works though.
Edit: Actually, I signed up for Robert C Martin's (Uncle Bob) new software training video site recently because his youtube ads were so silly. It helps that I knew his name long before though, and I've yet to pay for one of the non-free ones.
This is just a super common misconception among engineers that advertising is a very linear thing. Most ads are not direct response. Most of the time they're just trying to keep at the top of mind for specific groups of folks. So yeah you aren't going to just run out and buy a 20 million dollar piece of software because of a Youtube ad, but when it comes time to buy a solution in that space I bet you'll consider that product. When you think about the scale that this works at (It costs maybe a penny a view or $10 per thousand people reached) you really only need to hit 1 person at the right time across many millions upon millions of impressions to make it worth while. That's all. Many people just don't appreciate the scale of advertising and think it's more sniper rifle rather than carpet bombing especially for large B2B purchases.
I think it's not used more by big-co's because it's relatively a small audience.
Like I said I really like it but they have a ways to go to attract more mainstream users.
I've heard about testing ads for your various demographics before you go all in on an advertising campaign. But it sounds like there is even more to it.
Why do you feel like you would be useless in another domain? Surely you would do better than some geek off the street.
Across large groups it can approach being more formulaic where FB et al. will show you predicted # of conversions based on your inputs before you start a campaign. Of course you are trusting their estimation process then.
If I want to advertise my product or service I'm afraid it will just be me dropping a couple thow for ads that no one will ever click on. Maybe then the ad company would blame me for not having a compelling enough ad and I'll have just thrown away my money. I wish advertising were more formulaic so I had a better idea of how much I'll get out given how much I put in.
Alternatively, maybe online advertising can work if you think outside the box. But I have serious concerns about buying $2000 worth of customers from Facebook.