That’s not really a fair way to evaluate contracts for fairness and ethical conduct. Not only does the contract have the obligation to be clear (and let’s be blunt the people that do this are often not trying to be clear about what they are doing) it also needs to meet basic standards of reasonableness.
Specifically, to the extent that a contract diverges sharply from the general understanding each party has about how the world works, the more the drafting party has an obligation to clearly call out the terms in a manner commensurate with the importance of the contract term.
Legal documents aren’t software code, it’s a classic mental error developers make when discussing them. They are evaluated by humans.
For example, it would not be reasonable to have a single sentence buried in the middle of a 20 page SaaS contract that obligated you to purchase cat food, or signed away the rights to your apartment. Wouldn’t matter how plainly worded the sentence was and if it was duly signed. You’d still have to convince a judge that was a reasonable thing to do. Good luck with that. And regardless of legality it’s obviously not ethical it’s a trick, intended to be deceptive.
Obviously there’s subtlety to this and the exact details matter. But that’s my point. You can’t just fall back on the idea that anything you get someone to agree to isn’t a dark pattern.
The whole point of dark patterns as a concept is that you’re tricking people into agreeing to unreasonable things.