I agree with the statement that if the flight is of such a standard that you would not send the person solo I will not sign the log book. However I do treat the trip as instuctional and expect to have to go over parts of the flight and reteach as people forget over a two year period. I try and give the impession that the flight is help the person be a better pilot not a test he/she may fail, so if they have any particular things they want to cover/improve on please say so.