I have a theory that ads don't actually work to intellectually persuade most people to buy consumer products or services. However they do work somewhat on a cultural level to get people to perceive themselves as part of a cultural group and instill a desire to partake of the accoutrements of the group (e.g., NASCAR, sport team fans). The following comes from The New Ad Age:

It's the basic conundrum of marketing. You have to advertise to compete in the marketplace, but the more ads there are, the more people tune them out, so you have to continually find newer, brighter, shriller ways to get attention.

Meanwhile, as the advertising industry devises new ways to get its messages across, technologies are continually being developed that make it possible for people to skip or avoid ads. Online, you can use browsers like Firefox, which blocks pop-up ads. You can fast-forward previews on DVDs (as you have been able to do for 20-some years with videocassettes). You can skip commercials with TIVO (as, again, you have been able to do with shows taped on video). You can even share movies or TV shows online, ad-free.

These attempts to skip commercials offend some television executives.

"When we watch ads, we become the media's workforce," says Sut Jhally, author, media critic and founder of the Media Education Foundation. "They are, in effect, organizing our time. They have even said that there is an implicit contract with the audience. If a person chooses to watch a movie or TV, they say it's immoral to skip the ads."