-No clue where they are going (if they never driven on that particular road then fine)
This is something I try to be tolerant of - I'm not the hottest at reading road layouts I'm not familiar with myself and sometimes there is only arrows on the road itself which might be obscured by vehicles on top of them leading to confusion, etc. here for instance:
https://www.google.co.uk/maps/@51.0...4!1sVhVPXzsS2To1syImKO4ZfQ!2e0!7i13312!8i6656
If going straight on you have to use the right hand lane but it is only marked by that one set of arrows with no signs while the roundabout immediately before it you can use both lanes to go straight over so it would be easy for anyone new to the area to be confused.