Well up to a point. If the description, for example, includes a crossing of a creek (Gillan Creek) in a rowing boat with a man with a dog when at the time of the walk there existed a motorised ferry to take walkers across the creek, then it might be a valid assumption that the passage in the book was, er well, "embellished".
Fine, if that's what you want, but it can hardly in all likelihood be described as an unflinchingly honest account of what actually happened. Until the Observer article comes out, the jury, as they say, is out....