I'd not be so generous. Finish looks 50%, maybe. Vest pockets in this condition may very well have rust/pitting issues under the stocks. If considering purchasing have him take photos of the frame with stocks off. Ideally a photo of the pistol disassembled will tell you everything you need to know at a glance. My .02 worth
+1 with texasleguar, 80% is such a subjective value, I wonder why it is ever used to rate condition. I can see maybe 98+ratings (not this gun), which should be darn near perfect but used. As to it's value, that would be what you paid for it. % condition is a sellers opinion of what the price should be-he obviously thought his was better than it probably is.
A percentage applied to a gun is normally the amount of original finish left. I would suggest you look at photos or original guns to determine how they should look. A good example of finish grading is provided at the beginning of the Blue Book with color plates and grading applied to that photo. I don't like to get into other peoples business but since your post ask the question I would say less than 5% of the original finish remains and there is also some displaced metal around the serial number and it appears the trigger pin has been peened in place, not a good thing.
My 2 cents: 10-15% finish to my eye. As far as value/price, the first thing I would want to know is whether or not it has a Colt factory magazine. If so, and the bore was decent and the gun appeared mechanically sound, I would probably pay $150, but that's about as far as I would be willing to go. Someone else might pay $250. If it does not have a factory magazine, I just wouldn't mess with it at all.
Thanks to all for your replies.. It seems to me that this pc may well be a "parts" gun. Grips look ok, and if or when, I take it apart, I should be able to piece it out. Paid less than $200 It is the only Colt in the sad state of condition I have ever bought. Did it mainly to take it apart and educate myself on the workings of these little guys. It seems one can still buy superior examples of these little guns at reasonable prices with the"Colt" name attached to it..
Once again, thanks to all for your knowledge here. Fugio