I only recall one fictional guitar, and it would have a hard time qualifying as a "best". Would a "worst" be okay?

I don't recall the title or author of the book - just some cheap thriller type thing I read a few years ago - but the protagonist had a Martin D-28 custom built with a classical width neck and nylon strings. Now, have you ever, just as a lark, put a set of ball-end nylon strings on that extra D that's in the closet? The one you usually tote along as a backup guitar in case you break a string at a gig? I have. "Horrible" doesn't begin to describe the sound. Nylon strings have strong points and weak points. Dreadnaught bodies have strong points and weak points. Combine them together and you get all the weak points and none of the strong ones. Its sort of like using an outboard motor to power a washing machine. It can be done, but its noisy and inefficient and you'll catch a lot more fish if the outboard is on a boat where it belongs. Oh, I suppose the bracing pattern could be changed to improve the sound, but why bother. If nylon-strung Ds were a good idea don't you imagine one of the multitudinous guitar-makers out there would have one on the market?