I know a ferry pilot who never does USA-Europe jobs unless he can pick the plane up well inland before the US coast, so he gets a chance to suss it, over some hundreds of miles over
land, before heading out to Greenland. So he can see the oil consumption, etc. Apparently a significant % of ferry jobs which start right at the US coast are cases where a previous ferry pilot abandoned the plane because he didn't like something about it
100% right about checking a fuel totaliser. Again, this could be done over a single tank fillup. I know quite a number of pilots with totalisers and would bet that half of them do not use them because they don't know how to, or because nobody ever set the K-factor so the thing is 10-20% off.