I guess I should have expected a number of self-righteous replies from an enthusiasts forum. Obviously no one is going to confess to having had similar thoughts or to not having being 100% honest as it would damage their reputation, I am simply playing devils advocate and for that purpose set up an anonymous poll!!
The fact is a large number of cars up for sale privately are being sold as they have an impending failure, it's to be one of the primary reasons for selling older cars. The whole part ex network is riddled with lemons being off loaded as they couldn't be sold privately. If a dealer offered me £1000 part ex, should I turn round and say actually the tires are a little worn, the clutch slipping and I think the alternator's screwed, lets settle on £50, of course not.
I haven't actually decided what I will do yet, it's a pain as I was considering selling before I tested the coolant for hydrocarbons, the engine hasn't changed one bit since the day I brought it, the GTV has been constantly water thirsty for years and has covered many thousands of miles with me unknowingly driving with a potential faulty head gasket. It could continue for another 100,000 miles for all I know.
Now to sleep with a clear conscious I have to spend £2000 on it to (hopefully) then sell for £2500, obviously I can't bear to break it!