As far as 'working', it's just a guess. You'd have to put them in a wind tunnel to see for sure. There is so much going on before any air gets to the wing that the aero engineering has to be spot on. I figure for most wings it's about a 33% chance it hurts, 33% chance it helps and a 33% chance it does nothing. With aero, it's a lot easier to be wrong than to be right.
And remember that a wing vs. a spoiler accomplish different things- a spoiler is all about downforce where a wing is downforce + stability. Take a look at how the wings are set for qualifying at the Indy 500 - they actually tilt them back about 10* to take away downforce. But if they just took the wing off the car would be undriveable because you would lose the stability the wing provides.
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