I thought that they were the higher price for x amount of months (which no-one would ever dream of buying at that price) and then just get rotated around the store and put at the back when at full price then when it was that particular line's time to "come on sale" ie the correct price for the product, they marketed it like hell and had them at the front of the store, on TV, in the press, then mark it back up and its another line's time to "go on sale" Sure I read that on something like Money Saving Expert, and thats how they get away with it.

Supermarkets do it with cheap wine, labelled up to look expensive and mark it up at £9.99 for half the year, then the other half it's "half price" £4.99.

Quite often, the wine has reached the point where age-related improvement is at or beyond its peak and the wine can only deteriorate from then on.
When it was £9.99 it was coming up to or at peak-drinkability but, as that point is passed, the wine's storability is decreasing.
The same bottle of wine may have been £9.99 and reducing it to £4.99 does represent a substantial price-drop but whether it's a fair comparison is debatable.
From my point of view, if I bought wine at such a reduction, I'd drink it soon rather than store it.

Another situation I came across (not in a supermarket but in a "specialist" shop) was a wine with a large "review" card attached to the shelf where some wine expert had written in Decanter magazine (or similar) a recommendation for that wine but not for the same year of the wine that was on the shelf.
e.g. Let's say the review was for the 2006 wine but the wine on the shelf was 2007.
As chance would have it, they had a woman wandering that section and, noticing me browsing, she asked if she could help me.
I pointed out the different years and she either could not or would not grasp why it could be a problem.