Wine forgery and refilling bottles is a real problem for French wine. The biggest profits being made on the biggest names. Spain imports very little CduP yet you can buy it in many restaurants, it just doesn’t add up when a very limited quantity wine is readily available in a country way down the list of purchasing countries.
It’s not a question of a poor CduP, you’d have to be very unlucky and get a duff cork to get a poor bottle as the vigneron wouldn’t risk his appelation and simply bottle it up a sell it as Côte du Rhone.
I worked les vendanges at a Bordeaux Chateaux where they had two labels, only the perfect production that respected le cahiers des charges got put in the cru bourgeois bottles, the rest was sold as vin de Brodeaux.
A group of us had an MTB weekend in Spain. House wines were drunk initially, perfectly drinkable, then one of the group generously offered a descent bottle of French wine. Having lived in Spain I watched peoples reactions (clearly unimpressed) and then sowed the seed of doubt. Tasting became a lot more intensive and the collective verdict was that the wine definitely wasn’t what it said on the bottle and probably wasn’t even French.
It’s not just wine, up the hill in Spain I can buy famous branded whisky that tastes like nothing that’s written on the bottle.