Straightforward

"Bill: How about this? "Ocean Breeze Soap: It's just like taking an ocean cruise, only there's no boat and you don't actually go anywhere." Kermit: Seems a little long... Why don't you try something like: "Ocean Breeze Soap will get you clean"? Jill: You mean just say what the product does? Gil: No one's ever tried that before."

- Mad Ave Advertising, The Muppets Take Manhattan

Every once in a while, a manufacturer gets the bright idea to put a simple, concise ad on TV that describes exactly what the product is and what it does, and leaves it at that. Seriously! No CGI facsimiles of dead celebrities, no classical music remixed for inappropriate situations, no hackneyed demonstrations of competitors' products that insult your intelligence.

This sort of commercial is becoming exceedingly rare, as some collection of suits somewhere has undoubtedly decided that a commercial that doesn't provide some sort of gimmick or require a Hollywood feature budget obviously can't work.

Beauty and Hygiene

 * Medicinal dandruff shampoo Neutrogena has been fielding commercials for years with nothing but an image of the bottle (with the product glorping inside) and the tagline, "Neutrogena T-Gel: It works."

Clothes

 * While they've both devolved into gimmicky, nonsensical song-and-dance numbers, both Old Navy and the Gap used to air commercials comprising little more than people standing around in their brands of clothes.

DIY

 * Special mention should go to Ronseal, who for years have advertised their WYSIWYG-titled DIY products with the slogan "it does Exactly What It Says on the Tin."

Food and Drink

 * Marmite's slogan for a while was "you either love it or you hate it". In recent years this tagline has derailed into increasingly surreal comedy skits, such as a homeless man rejecting a Marmite sandwich and a big blob of Marmite emulating The Blob, but originally all that was presented was the jar of Marmite.
 * The slogan for Glaceau Vitamin Water is "Try it." Simple and effective.
 * Lipton's used a similar slogan when they tried selling their iced tea in the UK: "Don't knock it until you've tried it." The adverts themselves became somewhat sillier after a while, possibly because the Great British public did try Lipton's Iced Tea and began knocking it with great enthusiasm.
 * Subverted by Reeves and Mortimer's slogan for the Cadbury Boost bar. "Boost: It's slightly rippled, with a flat under-side."

Medicine

 * Head On! Apply directly to the forehead. Head On! Apply directly to the forehead. Head On! Apply directly to the forehead. Head On! Apply directly to the forehead. Please shoot me now. Head On! Apply directly to the forehead. Head On! Apply directly to the forehead. Make it stop, God. Head On! Apply directly to the forehead. (For those wondering, the reason it's advertised this way is that it's mostly a placebo, so truth in advertising laws prevent them from saying anything that would make you want to buy it.)
 * And let's not forget the commercials for Buckley's Cough Syrup, with the tagline "It tastes awful... And it works." and consisting entirely of people standing around and trying their medicine, and then making weird faces. Straightforward indeed.
 * Listerine mouthwash ran a similar campaign in the early '70s in which people would be asked how they liked the taste. "I hate it! But I use it, twice a day. It really works!

Restaurants

 * An old McDonald's commercial consisted of nothing but some guy picking up a Big Mac in slow motion. The commercial ended just before he got it to his mouth, making the viewer really hungry.
 * In the eastern United States, the Checkers burger chain ran a series of commercials that featured a guy sitting in a car, ravenously devouring what is obviously a Checkers burger. The guy is visibly (and audibly, though there is never actual dialogue) enjoying the burger, to the point that, when the burger was gone, the guy picks up the wrapper and starts picking the excess cheese off of the paper and eating it. Cue the voiceover as the screen goes dark: "Yeah... it's that good!"