Maybe not all of us have fallen for the pitch, but many of us have. We just couldn't help ourselves. The pitch was loud. Insistent. Demanding. If we called now, we'd get an extra set for free! Supplies were limited! All we had to do was pick up the phone now . . . now . . . NOW. Sure, we were initially hesitant, BUT WAIT, we were told. There's more! Dial 1-800-whatever-number-was-about-to-drilled-into-our-brains-over-and-over-and-over-again. And we did. The pitchmen - a phenomenon as old as American commerce itself - are masters of the hard sell. Ron Popeil may be the giant of the infomercial trade, and Ed Valenti may be its poet laureate ("But wait, there's more!" and "Now how much would you pay?" are lines credited to him), but Billy Mays was the Willie Mays of this exotic world. That black, almost pirate-like beard. That voice - the human equivalent of a 747 about to become airborne. Mays learned his trade from the pitchmen along the Atlantic City boardwalk, same as Ed McMahon, who also died last week. As Mays said in a recent profile, "I soaked it all up; how to get the crowd in, handle and control them, how to get them to pull out $10 or $20 on the spot. It was like they were passing me the baton." He and his pal, Anthony Sullivan, had launched a show on Discovery, titled (what else?) "Pitchmen." In a prelaunch interview, Sullivan was asked the secret of the trade. The product, he explained, "has gotta have mass market appeal, solve common problems, is demonstrable, new and unique, has a patent, and - as Billy says - 'KIS: Keep it simple.' " And yes, this is a simple business. There's an old saying in advertising: The marketeer knows that half of his advertising works, but just doesn't know which half. The pitchmen know precisely what's working. The phone rings after the infomercial ends. That's how they know. More than 5 million "units" of ShamWow, for example, have been sold on the testimony of someone named Vince Shlomi alone. This industry within the larger advertising industry is called "direct response" and has entered a boom period. As advertising expenditures have tailed off a total of 2.6 percent in the recession, direct response - characterized most famously by the infomercial and Billy Mays - has soared 9.2 percent, according to Nielsen. Icon Media Direct, a direct response marketing company, reports that ads done by Mays and Sullivan ran for 56,000 minutes on U.S. television last year, for a cost of $170 million. (Of course, they got a piece of the action.) Just before his death, Billy Mays was busier than ever.