Hello Ken
first thing i do is say hear the car start from cold and get that bonnet up and dont take any excuses from the drivers just up that bonnet and do your checks .. sometimes we have come across the bonnet cable cut on purpose to hide something so the bonnet cant be raised but this is normally on the older cars which we do buy so if in doubt walk away .. as we check for the tell tale head gaskets etc and front end damage .. personally i dont like to see a nice shiny steamed cleaned engine as why? .. to get rid of water/oil from leaks etc also engine management lights etc
if your buying cars in the price we do say £1000 up to £3000 then you are gonna get some problems from time to time .. im fortunate that i do the mechanics for us and have fitted clutches and cam belts etc.
personally we get a lot of ebay private sellers as you can really take you time and test the car .. ok our profit margins are not 7 8 900 hundred but good enough to buy private to re sell on