As one of, if not the, savviest collectors on this bored I’m surprised you believe this canard. We all know who we’re talking about here.
For the OP, my rules of thumb is that when buying older wine (at auction) I stick to commodity wines, like Bordeaux, and look for OWC. I will break this rule if there’s a particularly interesting mixed lot. I would only buy Burgundy in OCB and usually nothing with too much age (been burned too many times with bottles that appear perfectly sound, spinning capsules, etc. but when opened, wine halfway or more up the cork). I’ve been really successful with CA Cabernet back to the 1990s, but less so venturing into the 1980s and I’m not really sure why (maybe it’s just the producers I’ve bought).
This all could get better as time goes by because I think that, in general, people who buy and collect wine store it better than previous generations (aside from the odd Scottish castle cellar).