The simplest way to describe the bandwagon approach is peer pressure. The advertiser prints an attractive article with phrases like "See why more people choose (product name)." The intent is for the viewer to be encouraged to buy a product or service by believing that everyone else is buying that product or service.
The effect of the bandwagon approach can be likened to a formation of birds in the sky. The birds are on a course for a final destination, but each bird stays in the flock by paying close attention to what the bird next to it is doing. The entire formation is comprised of individuals who perfectly mimic each others' patterns to form and remain a flock. Humans have the same tendency to stay together and typically enjoy being one with their flock of fellow humans. This works out for advertisers who frequently use the bandwagon approach to convince us their product will keep us "one" with our peers.
There is an unlimited scope of options for advertisers to use bandwagon advertising in. Advertisements are often seen that make assertions in favor of the product they are representing. For example, an advertisement for heart medicine may say something to the effect of, "See why 3 out of 4 physicians recommend Pookie's Aspirin." The reader, concerned for his or her heart safety, will likely go for Pookie's because it is implied that Pookie's is the most popular, and thus the most credible option.
The point of the bandwagon approach or appeal is to keep the viewer's focus on what everyone else is doing--or at least what everyone else appears to be doing, as implied by the ad. Advertisers establish credibility by persuading the viewer to buy their product or service because everyone else does. The approach can lead to massive success for advertisers if they research carefully and use honest claims, as is demonstrated in books like "The Nature of Marketing" by Chuck Brymer.
Buyers should always research before assuming a product or service really is better. Unfortunately, some advertisers use bandwagon advertising inappropriately. They make false claims or greatly exaggerated ones by altering or bending the truth on statistics. It's worth the extra effort to look into the claims and use discernment to avoid being duped by less-than-reputable companies who use supposed mass-appeal as a product's selling point. It's wise to think it through and remember what everyone's mother has likely said at some point, "If your friends jumped off a cliff would you do that too?"