In my opinion, it's a complete
no-no.. as you don't know the original condition of the bag (ie. it could have been severely bashed/blackened/etc) and how the original owner(s) treated it. Since the restoration only 'glosses over' the faults, they can come through in a later stage.
I've also heard horror stories of restorations where the entire leather of the bag is
not the same as the original - all crackly and the smell is completely different. The original leather is what sets Balenciaga apart from other regular bags, so to me, "retouched" practically means "counterfeit" - I have a very harsh view of restorations, I know
If it's a mere "cleaned with soft cloth" and such, then I'm all for it. But when it's been spray painted, spray glossed and such.. then EEEEK!!!
Just my opinion though, many have purchased "restored' bags and been happy with it! i"m just a real stickler for the old lush leather - untouched