Noticing the OP is based in the UK, I'd be interested to know if your experience in these 'taste check' servings is primarily of wines of a certain country and if they are mainly red wines with corks - and the age of the vintages that you buy.

I ask because an interesting cultural difference is the tradition and prevalence of cork these days. In Australia/New Zealand, the Stelvin alumin(i)um closure has been tested, provben and used for at least five years, initially on whites and now almost always on all but the top reds, too, in order to eliminate almost all the spoilage previously attributed to corks.

Many red wines exported from down under are sold under cork (to US/UK/Ireland etc) even though they are much more popular now in their home markets under a twist cap!

My other point is that now that the cork is history (for us anyway, 80% of the time), we still have the taste test tradition, to ensure that the buyer/tryer is happy with the condition of the bottle of wine (as opposed to just liking the taste).

We're still enjoying some Hunter shiraz from 2002, still under cork.
So far, bottles from this case of wine has been OK, but one other red also from 2002 had a tainted cork on one we opened on NY Day.