I always recount the story of the Hovercraft Christmas.
There was one toy I wanted for Christmas. We were firmly middle class growing up, so it wasn't like I had all the toys, but I was old enough to know that my parents were footing the bill and getting an RC hovercraft was going to mean I only get one present that year.
Iirc it was called the Typhoon, or maybe the Typhoon II.
The commecials showed it zipping across land and water, jumping off ramps, bouncing off a lake, etc. It was the coolest fucking thing ever. I begged my parents for it, and would not shut up for months about getting an RC hovercraft.
Christmas comes, and wonderous joy, I got the hovercraft! Life is good, but the battery needs to charge. Shit, OK, we plug it in and let it charge all day while we go do the normal Christmas family visits. Everyone I talked to that day got a lesson in how hovercrafts work, and how it can travel on a pocket of air to move across land AND water.
We got home late that night. It was probably after 10pm, way past everyone's bedtime, including my parents who had been up all night making the Christmas magic happen for my younger siblings who still believed. But I put my fucking foot down. I had waited for months to get my hovercraft. I had waited all day for the battery to charge. I would not wait another god damned minute to go zipping around the backyard. So, my dad and I put coats on over our pajamas, went out to the driveway, and fired that bad boy up.
I can still perfectly remember the sound of the fans turning on, and the little rubber skirt inflating. Sure enough, the hovercraft was floating on a pocket of air! But the driveway was on a mild incline, so the hovercraft started to drift sideways. Then I hit the throttle and... nothing. Just the sound of the fans spinning, but no motion.
Bzzzzz. BZZZZZZ. Bzzz Bzzz Bzzz. The fans spun impotently against the inertia of the hovercraft. It wouldn't move at all, except to sadly drift towards the gutter. My dad gave it a little nudge with his foot, and it got stuck on a tiny stone chip.
I learned a lot about physics from that one night, but I learned even more about advertising.
Kirby vacuums. I got one for free from a neighbor and she included the invoice by mistake. $2200 for a vacuum that smells like burning and can't lift pet hair. Brush is working, bag is new, carpet is being lifted from the pad. But man, this thing fails at pet hair.
Air-up water bottles. When I bought mine it claimed to be a better water bottle all-around.
Its primary gimmick of tricking the brain into tasting the scent works well, I did drink a lot more water without needing actual flavouring. The fact that I could (unofficially) 3D print my own reusable flavouring pods to be a little more eco-friendly was a nice surprise and the reason I decided to try it.
The "better bottle" part is utter horse crap. It leaks when tipped over, even when tightly closed. Their marketing team went as far as adding "sip, don't tip" to the instructions instead of making the cap properly seal.
Drinking from it was a chore as there was no water pressure and the constant bubbling (lets be real, its more like wet fart) noises made it impossible to use in silent settings.
I ended up going back to reusing a disposable bottle until it leaks even though the thought and feeling of something flavourless being in my mouth is revolting (its a sensory thing).
Star Wars The Rise of Skywalker. The movie was already getting a bad rep pre-release, and in response to potentially sales-damaging claims that Palpatine was coming back, Disney had Ian McDiarmid explicitly claim he wasn't. A bad movie where there was nobody to point a finger to became a bad movie where there was someone to do it to. Then he passed away shortly after. I witnessed this mess all go down in theaters.
Remember how Google's Find My Network was supposed to be as good or better than Apple's. We put a tracker in a checked bag. Couldn't track it from once we lost sight till when it was 10 feet from me.
I'd already been doing contact juggling by the time the fushigi came out, but the ads implied that you could just... perform a skill by buying their product. It'd be like a company marketing the "mystical multiball" that shows people juggling 7 objects and implying you too could do that if you only owned their particular set.