Based on my experience with a related problem in standard exams...a good way to catch the OOC cheaters is to have a quest randomly ask one of several very similar questions. With chemistry exams it was almost too easy, I'd make two versions of the test, distributed to every other seat. One version had 56.8 grams on it and the one next to it had, say, 59.8 grams. Maybe three changes like this throughout the exam. Someone gets the answer to the other computation on their paper in a few spots, it was obvious what they were up to. (When I first arrived at my Peace Corps posting, I'm sad to say, I caught over a third of my class cheating this way!

)
Anyway, how this is relevant:
Someone gives the quest answer to ANOTHER question involved in the quest, not the one asked, they lose the quest forever. If they give a wrong answer, but not one of the other right ones, they get another chance later. Sticks for the naughty, carrots for the nice.
So, for example:
Player one
Bob the Barker asks you "What is round on top and has three legs on the bottom?"
"I eat fish, but never touch water. What am I?"
"The clock stopped at
midnight on the tenth day. How many hours had it run?"
Player two
Bob the Barker asks you "What is round on top and has three legs on the bottom?"
"I eat fish, but never touch water. What am I?"
"The clock stopped at
noon on the tenth day. How many hours had it run?"
If player two answers the last question with the answer to the midnight version, Bob howls "Ye wretched creature! Out of my sight, and never return again!" But if any other incorrect answer is given, he says "I think my questions be tiring ye. Ye have done well up to this point...why not return again in a fortnight and try again?" When they return, the question might be either of the two (or more) versions, chosen at random.
The q-log might even read "Bob the Barker suspects you of having tried to cheat in answering his riddles, and has refused to deal with you again." vs "Bob the Barker will eventually give you another chance to answer his riddles."
I realize this would be more work to code, but it would be very effective, I think!
Easy for me to say...maybe I should save my big ideas for when I get off the couch and write a quest, hmm?
Raona (not a coder...still a newbie!)