I was speaking meteorologically, not culturally! :-)
they basically don't turn on when they should. the windshield gets so wet that I'm forced to do it manually.
I recently took it in for service and then cleaned it "really good" and it worked better -- they actually would come on if I wanted past my comfort level but prior to my panic level (before I'd hit the panic stage of "OMG I CAN'T SEE".
I'm now experimenting where to place some electrical tape near/on the sensor to fool the system into thinking it is always wet. If I put the tape on it, maybe it will think it is always very wet. Above it might act as a "dam", building up water near the sensor to get them to turn on. i'm hoping that the sensitivity will then control how frequently the blades swipe.
btw, in the current configuration, I can tell no difference changing the sensitivity -- I assume this isn't what everybody else is running into.