The only soap I ever begged my parents for was Lava. I can remember using it in science class after a particularly messy lab. After learning this magical substance wasn't available exclusively in public elementary schools, I could wash with nothing else. I'm guessing this wasn't a hard sell, what with the price being in the $3 range and the benefit being a cleaner nine-year-old.
While I considered myself a Lava brand evangelist in the late 1980s, the power of the product escaped me. Here's a terrific 1950s print ad that connects Lava Soap with the eradication of Polio.