As college English instructor, I am programmed to spot semantic errors. I've observed, however, that various companies don't appreciate my efforts to apprise them of their egregious goofs.
Case in point: Recently I marched down to our local feed store to purchase suet for the birds. On the label I read the following: attracts a better variety of birds. Were they suggesting I had been feeding no account birds, birds from the wrong neighborhood? What they meant was "attracts a greater variety of birds." I wrote to the suet manufacturer's marketing department apprising them of their error. You'd think they'd be grateful. But no thank you, no appreciation. See if I purchase their product again.
Next I wrote to a cat litter company whose product ostensibly weighs 21 pounds. A note on the box exclaimed, "Up to 25% lighter, making it easier to lift, carry and pour." Using advanced calculus and a cheat sheet, I was able to determine that 25% of 21 pounds is 5.25 pounds. So, did I purchase 15.75 pounds of litter or did I purchase 21 pounds?
A man named Ken wrote back thanking me for my feedback and offering me oodles of coupons; he also explained that "up to 25% lighter" refers to other litter brands in similar jugs, that their litter is only 75% of their competitors' weight, 15 compared to 20, or 25% lighter."
This sounded a bit squirrely to me, so I asked a math professor his opinion. He responded, "they might think that what they said is equivalent to saying their competitors' product weighs 25% more (per unit volume), but it's not the same. If the latter is true, then their product weighs only 20% less, that is 25% more than 100 pounds is 125 pounds, but 25% less than 125 pounds is not 100 pounds." (Got that?)