How do you deal with the fact that sometimes it's more interesting for the party to fail a check?
I sometimes struggle with what to do in some instances where the party failing a check would lead to a more interesting interaction.
For example:
There is a merchant trying to trick the party into buying an item. That item is cursed, but the curse is just a slight inconvenience leading to funny interactions. If the party realizes the merchant is trying to deceive them with a successful check, then they don't buy it, and the potential interactions never happen.
Or there is a sophisticated mechanisms that, if triggered, traps them inside a room with a puzzle that requires some clever teamwork to solve, leading to a more rewarding feeling than simply succeeding at a passive perception check (which they don't even get to roll).
In both cases I want them to fail, because then the session becomes more stimulating. In my opinion, "Roll passive perception -> Success -> There's a trap here -> Ok I avoid it -> Next room" gets a bit boring after a while. But I feel like fudging dice or setting a DC that is impossible to beat goes against the TTRPG spirit. I could also simply "force" the interaction without a check, but I'm afraid that would feel unfair.
So, would you guys have any advice on how to introduce "bad" but funny and/or stimulating interactions without having the party find out it was "forced"?