Because it has no proof of ownership? Cue thoughts of theft, insurance write off / VIC inspection needed, hence explains no V5. How hard can it be?! Price reflects, and you take a chance!
Ah yes, didnt see the amended thread title. Still, its not "that" cheap. A friend brought an 8v GTI back in the day a few years ago when you could still get Mk2s for a bargain. He paid 50 for it. That was cheap.
We bought my girlfriend's scirocco almost 7 years ago now for 500, it came with 2 sets of wheels - we sold one set for 100. When we checked the receipts that came with it there was one for a brand new stainless exhaust for 380 which had the mileage on the receipt of 500 miles less than the mileage when we bought it! For some reason sciroccos are unloved by many!