The worst thing I've come across is an automatic staple remover.  I used it for the first time on a big report I had to give to my boss.  It grabbed the paper and tore the first few pages (important pages).  I was glad I hadn't bought it with staples coupons ( http://discounts.shopathome.com/Coupons-Staples.discounts/5424/ )
rather than at full price because it would've been an even bigger waste of money.