In one of my (now ancient posts), I got an oil warning light on the M6 motorway, I called in at Blackburn Audi who were very helpful. They couldnt read the dipstick, so took it into the workshop, after an hour they said it needed a litre of oil, for which there was no charge and wished me a pleasant journey. So top marks to them.
On arrival home I took it to my dealer and asked if they could explain such a massive rise in oil consumption, unfortunately England were playing footie on the telly, so I was as welcome as a boil on the posterior. Reluctantly it was taken into the workshop where they drained an excess of 1 litre of oil, and advised that the oil warning light was easier to read than the dipstick!! No problems since.
So yes the dipstick is useless unless your oil is so dirty it needs changing anyway, even then it's difficult to read.