This sort of thing has been going on for years, its just moved on-line now, which makes it even easier to hide behind it.
Macro always had a brilliant offer on the front of their monthly newsletter, but when you got to the shop, there were never any left (i think they stocked one at each shop just to stay inside the law) but of course there were always lots of very similar items at a higher price, or usually, lower spec items, which looked essentially the same. Either way, not as advertised.
All retailers will use "loss leaders" in this way, so its a case of Caveat emptor. Still, we all fall for it now and then, so its worth them keeping doing it.
I saw a TFGear 8/10ft All Rounder rod in the Bargain Hunter section of Angling Times last year. It was advertised as being £59.99 direct from TFGear. I'd been thinking about getting one, and this was a tenner cheaper than I'd seen it before. So I visited the website. There it was. 8 in stock at £59.99+ postage. Then the page refreshed. Suddenly it was £29.99 + postage with just 6 in stock. I ordered one and quickly posted on here about it. At least one other member on here got one that day, because he mentioned buying the last one. TFGear were closing down and selling off the remaining stock at rock bottom prices. Thing is, this was on a Monday. I subscribe to the AT, and some weeks my copy arrives on Saturday or Monday, a day or two before it hits the newsagent shelves. So anyone buying the magazine on it's official publication day, would have found the rod already gone, and never to return to stock. About 2 weeks later the TFGear website closed for good. So that shows how up to date or rather not, the Bargain Hunter section can be.