My own experience shows that the quality of ads, ad targeting, your website, your brand, your product, etc.. all affect advertising return-on-investment. I can

My own experience shows that the quality of ads, ad targeting, your website, your brand, your product, etc.. all affect advertising return-on-investment. I can see my ad return improving every time I improve the quality of one of the above. You can spend a million dollars on advertising and get zero return if your product is absolute crap.