Weatherproof Solar Powered Lights?

As I’m watching Discovery HD Theater tonight, one of those “As Seen on TV” type commercials comes up for solar-powered spotlights for your yard.

They advertise them as totally weatherproof, but I disagree – they won’t work if it’s always cloudy, raining all the time, duststorm, tornado picks ’em up. They’re pretty damned reliant on the sun, yes?