The thoughts from customers about wines, some of which fall into the complaints department, are reasonably predictable. Mostly they tell me that a wine they have purchased is not to their liking. Some alas lose the plot and tell me I do not know what I am doing.

Because wine is an odd consumable about which there are many opinions Glug, and most retailers, offers a money back guarantee.

Tasting and making a decision about the wine is not as simple as it may seem. I like to say that wines are friends as unlike humans they do not vary, and I like to say, 'let the wine talk to you'. To translate, if you like the wine one month and not the next who has changed?

I spent a decade behind the shop counter in Canberra and noted that at best only a few dozen customers really understood wine. To help customers understand wine I have been placing my thoughts on Glug for 11 years in the section 'On Tasting'.

Here are some recent comments:

"To whom it may concerns,
I'm writing to you to let you know that I'm very disappointed in the quality of the "Postcards 'Aerial Firefighters' McLaren Vale Shiraz 2013"! I opened a bottle a few days later after I received my order in December, my wife & I couldn't finish half of the bottle, it wasn't easy to drink at all, the wine has no balance & the sourest stays in the mouth down to the throat, it was a terrible feeing! You may ask why I remember so clearly, because I opened another bottle last night, I had 2 glasses of it in 2 hours & hope to see some changes. Disappointed!

Therefore, I reckon the description of the wine is over-rated on your website, if it was really $24.99, I'd have many options, but not this wine for sure!!"

Reply: Your note has been forwarded on to me to offer a reply - though I am unsure if you want one. As you know I began in the wine trade in 1975 and am pretty sure now I know what I am doing.

That opinions differ about wine is commonplace. I have written on the Glug site for many years under the title On Tasting. Here I attempt to give my knowledge and yes, the wisdom I have learnt over my long career. At the very least all is not what it seems about wine.

Thus we differ as I have no doubt at all that the wine you dislike so much is one of the best wines I offer. It was made by a very gifted wine maker Nicholas Bourke and I know he also is very proud of the wine. So what does all of this mean? Alas it is hard to say.

The wine is though quite young and contains no sugar. Apart from that it is typical McLaren Vale and has a great future. If I was to hazard a guess it is the aggression of its youth which does not appeal, otherwise, I have no answer.

I will though credit your account for the three bottles. From your part perhaps glance at what I write and perhaps not be so hasty in telling an old wine merchant that he does not know what he is doing. I have no doubt I am one of the best in this business.

Later I made the remark that 'To whom it may concerns' has addressed his views to himself.

"Let me introduce myself...... a very good client with an appreciation of the old wonders of the Barossa in the form of the Grenache and Mouverde varieties you have so persistently educated myself and my neighborours with. But a small complaint about the 2008 below.

P.B. Burgoyne 'Reserve' Barossa Valley Shiraz Grenache Mataro 2008 Previous bottles bought were fine. 2 last year I think. But this batch is different. I have opened 2 bottles and whilst the quality originally undeniable, my main gripe is that even allowing for fading fruit, each bottle opened (2) had a sour taste, enough to draw negative comments from the neighbours and to have wine left in the bottle. All in contrast to the wine I had last year. Don't feel like opening the others....

What can we do? I'm open to suggestions?"

Reply: I take your thought very seriously so it has taken awhile to put together what I want to say. Your observation is not unusual and I will reuse some of this in a future article in my long, ongoing 'On Tasting' columns posted on Glug.

With that said you introduce yourself in such a mannered and gentle way that it's a pleasure to reply. The rants and raves I all too often get still amaze me.

I do make some pointed comments though these are done in the spirit of informing, and while risky I have decided that since I am approaching 70 I might tell a bit more of what I have learnt, at the risk of offending.

I would be pleased if you glanced at my writings under 'On Tasting' where I describe what I know and the numerous pitfalls that await tasters. This section as with much of the commentary on Glug is to assist customers to enjoy wine, just a bit more.

It would seem such a little thing to make your own opinion about a wine but I have found it all too often leads to very odd results. I am unsure how advanced you are in the use of masked tastings but they reveal truths quickly about the fallibility of humans.

Possibly you read that I looked at this wine over Easter with a wine drinking friend. I found it wonderful and he promptly purchased a case. I passed this on to customers as useful new information to assist in purchasing.

The wine was purchased from a Barossa artisan as my notes say. There was only one lot and no different batches and it was already in bottle. I have never seen any variation over the years and the bottle at Easter 2014 was fresh and young with no sign of fading fruit. I generally prefer younger tastes as the promise of age is seldom delivered so I was pleased at what I found.

I have a saying about wine which goes; 'let the wine talk to you and do not talk to the wine'. They are reliable friends and cannot vary though they ever so slowly fade. All our wines are bottled under screw cap as corks are stone-age material and this has delayed the fade of age even more.

Not being with you I cannot of course say what you tasted but if I was to hazard a guess I would say the humans got confused. We are so unreliable in our observations yet so certain in our pronouncements about many things let alone wine.

Ben and I consider ourselves professionals but as Ben reminded me a moment ago he has terrible days when he knows he should not make assessments about wine.

Our moods alter, emotions rage, we get swayed by opinions of others, what we have eaten varies; the list is endless though mostly it is the brain playing tricks. I find, as I live in the Barossa, the daily tasting and drinking of warm climate reds gives me all too quickly a 'cellar palate' and find the adjustment to say the wines of Margaret River requires all my abilities to re-calibrate.

This ability to change rapidly between wine styles is the mark of the best drinkers.

But I again remind myself I was not at your table and have no idea why the wine seemed off and sour. Any Barossa wine being seen as sour is itself odd as we are the home of big, warm, rich wines and 2008 was of course a vintage of large, warm, sweet styles.

I repeat myself by saying take no offence at what I have said as I am quite clinical in my thoughts.

As you are aware we have a full money back guarantee so perhaps try another bottle under different circumstances. The best way is to let someone else present the wine to you without you knowing what it is and see what happens. If it is still off simple email Ms Fix-it, Nicole at Nicole at glug.com.au and she will arrange a full refund and a pick-up of the remaining bottles.

Again one last example; finding the same wine from the same box varies a lot is quite common and recently a customer complained that after a long stay in France he found the wines from Glug had gone off while he was overseas.

Indeed they are different as he had adjusted to the much cooler, lighter, acidic tastes of French wines, something I have also noticed myself innumerable times, and could not understand warm climate wines upon returning.

The winemakers of the Yarra no doubt detest Barossa wines which highlights in my view one of the great difficulties in general wine judging. This and many other aspects I cover in 'On Tasting'.

One of the sad aspects of being a wine merchant is observing customers drinking the same wine repeatedly because they cannot adjust to the idea of a different taste which may not give the same pleasure. They purchase the same wine every order till it runs out when everyday variety and the difference is the way to go. A household interested in wine and food should hold numerous mixed cases covering many varieties and regions.

As a rule the adage that the customer is always right is the correct approach. As I have got older I find I break all manner of rules but this conversation with you is the same as I would give anyone wanting me to chat about wine so I want you to see this as me just chatting to Mr and Mrs Smith.

I hope these thoughts assist you and will leave the final decision to you.