I don’t often whinge – I think!
When it comes to corked wine, my average is only around 4% detected – close to, but at the bottom-end of the rates from most studies – so I don’t consider myself a hypercondriac.
My approach to merchants when I have a bad bottle is simply to point out the problem and in a friendly-way ask (where possible) for a replacement, no histrionics, no emotion. The level of professionalism that merchants display at this juncture usually defines the longevity of your/my relationship with them – that’s my experience anyway. Those that can swiftly achieve the replacement, without fuss – I don’t need an apology as it’s clearly not their fault – tend to be my main suppliers, those that cannot are quickly ‘discarded’.
Why discarded? – That’s easy; there’s a big difference between ‘fault’ and ‘responsibility’. There is no blame attached to a bad bottle, but in a commercial transaction there is a responsibility to supply product (any product) that is fit for purpose – if it’s faulty it needs replacing. One ‘specialist’ merchant in my country of domicile points to the fact that their low (merely average) pricing does not allow for replacements – tant pis pour toi – they no longer have any business with me.
There are grey areas (of course) like when I had a bottle very recently with two winemakers; the bottle was clearly corked. I made my normal request and had the following experience:
“Do you still have the bottle?”
“No, I opened it in Burgundy and chose not to drive 260km back to Switzerland 4 days later with the faulty bottle and its contents” (which is anyway still 150km from the merchant’s location – I wonder if I was expected to post at my own cost an already opened bottle?)
“okay, I’ll have to check what we can do with my director – because this is an expensive bottle” (€90)
We anyway agreed, without further comment on what the ‘director can do’, that I would pick-up the replacement at a tasting. I got the bottle, but also with a note saying that I would be charged at 50%. Hmm. I have not yet made a fuss, because I have not yet been billed. It is also quite possible that I would have had 100% refund if I had been able to produce the bottle and its bad contents – though this implies a certain lack of trust and definite logistical issues. For now I will keep my powder dry, but a similar such occurance will certainly be the last with this merchant.
Personally speaking, only a portion of my faulty bottles will ever be replaced, as I only see it in the young wine when tasted at my first purchase. Once the bottles have lain in my cellar for more than a year – even if the problem is TCA (which will have been there since bottling) – I become philosophical and tend to agree (possibly wrongly): tant pis pour moi!
I think I’m very fair, I know that some people would say overly-so (?)
It’s not so long ago that I 
Wine #7 of my pre-Christmas Pommard odyssey