Why, because there are many measures of success. And this goes back to my Advertising 101 Article previous to this post.
You see, before you can say it was successful, you have to know what you are trying to do. For instance, if you are trying to simply drive traffic to a website, this is one measure. If you are trying to create sales, this is another measure, if you are trying to create brand or name recognition yet another. If trying to generate contacts or conversions or eCommerce business, all of these are separate measures.
I can tell you, that not all are the same, and certainly expecting Amazon or Ebay results are probably foolish in design.
The typical business wants to increase sales through advertising, thus getting people to your site, that don't convert into a contact or a sale, does not meet your needs.
Having owned a business that hosted hundreds of thousands of Websites in the past, I can share some tips to improve what is known as conversions, (contact to your business)
1. Design of your website. You must put calls to action on as many pages as possible, don't rely on a solo contact page. Offer something to get them to contact you. In addition, many sales questions are going to be answered by your website, without the benefit of being able to explain why you are better in person. So make the site dynamic and answer those most common questions. Add credibility, longevity, quality and price points if applicable.
2. People are very specific in searches, so having someone search for a specific item and land on a page that is general in nature is a sure way to get them to leave the site and look at the next one in the search. For example, someone who needs brakes and searches "brake repair in my area" and sees for instance a Firestone ad at the top, then clicks and gets the main page which talks about tires, is a waste of money. They want brakes, they need to land on a page that talks about brakes only. These are called landing pages and should be attached to any ad words you buy that are specific. The conversion rate will rise by 300% or more if they land on a specific page to their search.
3. SEO or organic search comes down to how many credible links from credible companies you have on your page. Most successful organic SEO websites have hundreds if not thousand of these. Make affiliations with companies like Amazon and Ebay and Google right on your page. Also keywords are important, but they do not come close to links. Add your verticals association links, vendors links, manufacturers links. And you will climb the free search ladder.
But remember, before buying Ad Word, building Facebook and Twitter and LinkedIn pages, know your goal. What do you want all of these to do for you and design these pages to that end.