Marketing by nature is deceptive
Not true.
OK, would it help if we changed that to 99% of marketing is deceptive by nature.
For every marketing campaign that is honest, there are 99 that aren't. I cant even think of a marketing campaign that is global and honest. Every one tries to convey an impression that isn't true. Axe/Lynx deodorants wont make you irresistible to the opposite sex, drinking coke doesn't mean you're doing wacky things with attractive friends, every airline advertises flying as a pleasant experience in half empty cabins, not being crammed into a cigar tube with 300 others a recliner in your face, a kid kicking the back of your seat and some idiot cropdusting rows 34-47 every 20 mintues. Honesty in advertisement is a big problem because the honest truth is that products are not that good.
Would you buy a Mercedes if the ad said "Not much better than a Nissan, but twice the price" or coke if it said "We'll give you Type 2 Diabetes, but you're hooked on sugar anyway"? Of course not, honesty is an pariah for advertisers.