When people read that a generic cologne is chemically indistinguishable from its overpriced, name brand counterpart - so much so that '75%% of consumers can't tell the difference!' - they are banking that you'll want their cheaper product instead. Or that the $39.99 purse you see at a mid-tier clothier has '99%' similarity to the $500 Coach alternative, they anticipate that the comparative breakdown will drive home the point that it just doesn't make sense to buy high.
It's a one-two punch. Appeal to what you want by showing how much you save.