My only experience was when I hitched across the 'States, got a lift in a truck and was asked to drive for about 300 miles. When we swapped back the guy asked me how long the brakes hadn't worked properly to which I replied that I thought they were meant to be spongy!
Luckily he was a mechanic, had all his tools in the back so we pulled into a rest stop, stripped a wreck of it's brake pipes and were back on the road in a couple of hours!