I'm also not a lawyer, but I don't think its ever a reasonable defense to say that you didn't know the terms of the contract if you've signed it (or agreed to the terms online - which I'm sure is provable by Adobe)?
While this case may be hard I'm pretty sure it isn't "never". For example if you are buying a subscription to a software suite and they sneak into the contract "You also give us your house" that isn't going to fly, even if you signed it.
E.g. if ToS said I needed to give up my first born to Adobe, the judge isn't going to side with me because I didn't read the ToS. They will side with me because the clause isn't valid.
I'm not sure if this would fall into the same boat, but if the dark patterns get misleading enough, there is a real-world risk that the contract would fall into the same situation: misleading enough that the hidden portions of the contract can't be applied.