I hate "up to 50% off", "reductions of up to 50%" or "up to 50% off and an extra discount of 15% today".
(a) the first two are meaningless, and the retailers know this.
(b) is the 15% off the already-reduced price, or off the full price? So if there was a product with 50% off, is it now 35% of the original price or only 42.5%?
And worst of all, there's the "up to half price sale". Does this mean prices are no higher than 50% of the original price, or no lower than 50% of the original price? In other words, are the prices up to half original price or are the discounts up to half original price?