The forward march of the sovereign wealth funds seems in slight disarray these days. Some have been lured off the track by glittering baubles such as football clubs and trophy buildings. But even the steadier troops face a wider issue. How far can they count on seizing assets from the stricken west on the cheap?

To pose the question more generally, in what circumstances can foreign buyers identify value not perceived by the locals? The burden of proof, after all, is normally the other way round. Too often, foreigners only discover why the locals were selling after the deal is done.