A few years ago a friend of mine had a 205 gti, which he decided to spin on a corner hitting a lampost and writing the car off, When he claimed thou' his insurance they under valued his car because it was previously written off.
Due to the fact that he purchased thou' a dealer he was seeking legal action agaist the dealer because he was sold the car not being told it was previously a write off.
This turned out that my mate did not have a leg to stand on and the dealer did nothing in law wrong, they are not abliged to tell you that the car has any previous history.
This is why a £10 - £20 check is worth purchasing before making a desion on a vehicle and do an independant one yourself, and you will see the true history plus you will be insured agaist certain aspects (ie the information provided porves to be wrong)
This being said, I would happily buy a repaired writeoff, however would probably want it double checked out and the money must reflect the previous history as you would have to discount it for the same reason when you come to sell