Good or Bad Marketing?

Not too long ago, I was Google-ing some images for my Assignments, stumbled upon this.

As a Marketing Student, I was frustrated when seeing this kind of promotion, but then again, it is funny when you really pause and think about it.

Well, I assume the promotion is 'BUY X FOR THE PRICE OF X - 1', or something like that, this might just be a misspelled banner or some printing error.

I wonder, were there anyone who fell for this? Haha. Well, I would like to buy 3 big bottle for the price of 3 small bottle though.