I think advertising works best when you don't actually care what you're buying.

You're in the toothpaste aisle at the store. There are 47 different brands that all cost $3 for a tube. It literally doesn't matter what you buy, they're all fine, and if for some reason the toothpaste is awful in some way, you are not out much money... and even then, even the most avid tooth brusher is only affected for four minutes a day. So you probably buy whatever the manufacturer paid to have placed at eye level, or what you have a coupon for, or what you saw an ad for. Yeah, you're being manipulated, but does it really matter? The only thing it really does is raise the barrier of entry for new manufacturers of toothpaste; until they can make their manufacturing process as efficient as the competition, they will not be able to spend as much on advertising. It is unfortunate, but what can you do? The tubes of toothpaste have to be presented in the store (or online) in some order, and the store makes more money if they just order it by amount paid. I just don't think there's any way you could ever get around it. And, of course, if you have strong feelings about toothpaste you'll just ignore the ads and buy the kind you like.

It also works for things like online stores. If you have a specific product in mind but you're searching for it, you probably don't super care where you buy it from. Especially if you look at something like cameras -- the manufacturers all specify minimum prices, which everyone sells it for, so it doesn't cost you money to buy it form store X instead of store Y. So you just go where you're told to go. Again, some stores have enough profitability to be able to keep the lights on AND buy an ad, while some don't. It's not really your problem. If all the camera stores went out of business because ads were too expensive and they couldn't get business any other way, you would just buy from the manufacturer. The ads just serve to make a decision for you that you obviously don't care about.

Then there's a third category, things you actually care about. Say my keyboard broke and I wanted to buy a new one. I didn't forget everything I know about keyboards. I know I like Topre switches better than Cherry switches, so that pretty much limits my choice to a handful of manufacturers. If I was searching for a Topre keyboard and saw an ad for Cherry keyboard, I probably won't give it a second thought. I already know what I like and no advertising is going to change my mind. And indeed, if I search for "keyboard" and click through to shopping, all the ads are targeted at people that don't care what keyboard you get. One is a piano. The next is some glowy thing that connects to your iPhone. Then there's one for $2.99. If you don't care, this probably helps you get the decision over with and some sort of input device in your hands. I wouldn't enjoy a $3 keyboard with free same-day delivery (how can that possibly be profitable, btw), but the ads aren't for me. For someone that literally doesn't care, the $3 keyboard is probably the right choice. I'm sure the $3 keyboard that doesn't have an ad is slightly better than the $3 keyboard that does have an ad... but it probably doesn't matter.

I dunno; the TL;DR is that I don't really care about ads. Either something matters enough to spend hours reading forums, asking friends, shopping around, finding somewhere to try before you buy... or it doesn't matter enough and you just take what you're given. Either way, I don't feel that advertising is ruining my life in any way. Yeah, we should probably spend the money inventing some sort of cure for all known diseases or feeding the poor... but I doubt that if advertising went away that's where the money would go.