I've only had demo flights when seriously intending buying. What are you wanting from the purchase? That decides what you do. What the seller wants to do doesn't matter. I've never logged such a flight.
After a friend's horrible accident many years ago, slow flight and stall characteristics are always a priority for me. (i.e handling near touchdown - tested at altitude)
And if it's not new - check the log books. Then get a suitable engineer to check it and the log books.
Last edited by Maoraigh1; 17th April 2012 at 20:22.
Reason: Addition