When you go to look at the car, disconnect the HT lead and turn the engine over on the battery. What you are listening for are equal compressions, and not one cylinder 'missing' its stroke. Very difficult to explain in words what I mean.
You should hear, 'duh, duh, duh, duh'. If you hear 'duh, duh, duuuuuh, duh, duh, duh, duuuuuh etc' then you have a cylinder obviously with low compression causing a mis-fire and you walk away. If it sound even, then the chances are that its a simple cure like a plug, or a lead, and if the price is right, it may be worth a gamble.
(Don't take the piss the rest of you because of my duh, duh, duh's!)
