The trouble with some Energy Guides.(dishwashers)

Carol Pogash was dismayed when she recently took delivery of her new dishwasher. A resident of Orinda, in northern California, where electricity prices have soared in the last two years, she had ordered the Sears Kenmore 1563 sight unseen because our May dishwasher report ranked it most energy efficient for the least money of the top 12 machines.

When she unwrapped her dishwasher, however, she learned that the government's EnergyGuide, the bright yellow sticker on large appliances that helps shoppers compare energy usage and expense, ranked it an electricity hog.

Moreover, her dishwasher did not carry the coveted Energy Star, which the government awards to energy-efficient appliances. "I felt cheated," says Pogash, an editor with Forbes ASAP. Annoyed, she asked us about the discrepancy.

The explanation lies in the flawed testing procedure for the EnergyGuide program, whose data are also used in granting Energy Stars. Dishwashers are tested with full loads of completely clean dishes, which skews the results. That's because many dishwashers (roughly 40 percent) now have dirt sensors, which allow clean loads to use a lot less hot water--and therefore energy--than dirty loads.

When we tested dishwashers using very dirty dishes, ...