ON FIRST VIEWING, AN INFOMERCIAL may seem as strange a beast as, say, a game-show miniseries. But these half hour-long hybrids of advertising and programming, already familiar to late-night insomniacs, are popping up more frequently in daytime hours on cable and broadcast channels, usually as ersatz talk shows or newsmagazines. Everyone has mistaken couch-perched Ali MacGraw and Meredith Baxter for standard talk show guests—until the talk about cosmetics went on and on and on.

Infomercials were born in 1984, when the government ended its 12-minute-per-hour limit on TV ads. Six years later, the "shows" (for which the infomercialist buys the airtime) were raking in a reported $500 million in sales of products, some costing up to $180.

Stars are singing hosannas to financial plans, car wax, male-potency preparations and weight-loss systems. Why? Mostly, it's not to bolster sagging careers but, as an infomercial might put it, "to maximize hidden earning potential." According to Greg Renker, president of Guthy-Renker Corp., a major producer of the ads, participating celebrities might be paid as little as $5,000 up front but can earn a big chunk based on sales generated by the spots.

There have been grumblings, both from consumers and the Federal Trade Commission, about unfounded claims made for some products (for instance, a diet-device "show" featuring Michael Reagan was withdrawn after an FTC challenge). And infomercials haven't always been labeled as such. So the National Infomercial Marketing Association—a self-monitoring (but technically powerless) group of producers—has recommended that, at the least, these shows should carry a label.

Meanwhile, one cable network has plans for an infomercial channel. Now, that's a beast.