It's pretty easy to spot dark patterns when you look out for them, but I found a pretty obvious example of this.
Stoofie is a brand that sells water fountains for your pet (I don't know what the problem with a water bowl is, but I digress). WayBack Machine
Plastered at the top of their website is "33% OFF Ends Today- Free Shipping" with no way to dismiss it. There is a scrolling text under the main image "FAST AND FREE SHIPPING 60-DAY FREE RETURNS"
If you scroll down, you're immediately introduced with a product with the option to buy two preselected. The rest of this section explains itself:
Other things are sprinkled in the main page, but it really is the prime example of dark patterns. I am personally sick of finding them, but would love to see more examples of what others have found. Please, share your favorite examples of dark patterns. Don't forget to archive them first so they can never be lived down.
I'm honestly surprised no-one has built an extension to automatically opt out of them, or at least the major cookie providers interfaces.
I realise there are many extensions which outright block cookies, etc; I'm meaning specifically the annoying dialogues you describe
In ublock origin settings. There is an "annoyances" group with options. It should take care of most of those popups.
https://addons.mozilla.org/en-US/firefox/addon/consent-o-matic/
Aarhus university has done exactly that! https://consentomatic.au.dk/
It doesn't work 100% of the time but it's pretty good