I have bought 3 items from one of those infomercials.
1. Some steam-making contraption that was supposed to curl your hair. It had some chick from the soap "Another World". My curls came out limper than over-cooked spaghetti.
2. Winsor Pilates - I LOVE IT! It seriously tones up everywhere (I used several dfferent WP dvds.
3. Proactiv - women often develop skin problems in their late 20s, and this is the first thing that worked. You just have to use it faithfully. The cost - about 20 or 30 bucks a month - is reasonable because i easily pay that much for scrub, face wash, astringent, moisturizer, etc.
Other than that, I have flipped to an infomercial late at night when I can't sleep and nothing is on. It's quite entertaining.
