That one isn't the fault of the sat nav the stupid cow parked on a railway line!
Have had probs with them myself especially in Portugal. Portuguese road maps are complete sh1te so use the sat nav a lot over there. The only problem is their road network includes a lot of old mule cart tracks that aren't really suitable for the average hire car.
While following Wellington's line of march on an 1810 era motorway I found an 18 inch drop in the track - not somethng the hired Nova could handle, so had to do a three pointer amongst the olive trees and reverse track for several klicks and find an alternative route. This still wasn't much more than a cart track though. If only the rest of the world had the same as OS!!!
Trusting satnavs is all very well and good. I bought a Tomtom before coming to deutscheland and it's worth its weight in gold, a little bit of common sense every now and then doesn't go amiss though, like when it says turn the wrong way down a one way street (not that often)
People who follow them blindly deserve everything they get.