The check list you refer to, is plain wrong, regarding Renting a boat, there is much much more information required. A lot of special permissions are now needed, from C&RT for a start.
The condition check list is ok, certainly better than most I've seen, you are looking for signs of being well cared for, not recently "tarted up". Being shown around by a knowledgable owner, rather than salesman is a great help. Smelling is your greatest asset, damp and loo smells, along with "air fresheners" are danger signs.
Bod