Found these notes via Google:
For the most part Hobies are pretty bullet proof, I raced them for
five years (in fleet one) and knew Hobie Alter. Some signs to tell
you how the boat was taken care of are:
1) Is the hull stiff? It should be, any flex is bad and may
be a sign of the boat sitting along time.
2) Is the bottom of the hull chewed up? If so, it might have
been dropped or dragged a lot.
3) Are the hulls the same? Sometimes the dolphin striker breaks
and the boat folds up and people replace one of the hulls.
4) How tight is the tramp, and rig, is the mast ok (look at the
rivets and screws for excess corrosion, also look for salt/sand
buildup everywhere to see if the owner cleaned it with fresh
water after every use). Looseness in either says unused and
poor maintenance.
5) If someone says he races it then they probably took better
care of it and it might come with more gear. Check to see
if the blades are sanded and if the sails were off the boom
and rolled for a quick, yet incomplete, affirmation.
6) Check out the trailer, bad ones abound and may be expensive
to fix or replace in relation to the boats price. Salt really
does bad things to bearings.
7) Sail a new cat as much as possible, demos from a shop, or go
out with the racers if possible. Then sail anything you're
considering buying. Mabey it's more than you bargained for.

Don't forget how you would buy a used car and apply the same
thinking.