Not long ago, I was given one of these gizmos. It's a little alloy slug that looks like copper that's swaged into a stainless steel dipper. The idea is that a brief dunk in a sample of wine (1 second for 50ml) approximates one YEAR of bottle aging. It's touted by the manufacturer and retailers as an easy way to tell if the wine you're tasting today will be worth cellaring, and for how many years before the wine's quality peaks.
I have played with my Clef du Vin for awhile now, and I think there is something to this. It certainly DOES change the overall impression of wines, improving most reds for a few "years", and then the quality falls off rapidly. There is great variability between wines, and repeatability in different bottles of the same wine. Some wines have shown a double-dip, just as the manufacturer claims.
I've even used it to try to "advance" young bottles at table, with a fair degree of success.
I know people debate the reactive chemistry theory (allegedly) involved here, and disagree whether and how the Clef du Vin actually works. But here's my real question: Is there anyone out there who has been BURNED by using this as a buying and cellaring tool? In other words, has anyone bought wine in reliance on it working, and had reason to regret it? If so, why?, cellared too long?, wine never aged as predicted?, tasted worse than predicted?, etc.?