Use descriptive user-readable labels and look at emitted events to understand which property failed.
If you are using event-based assertions mode, you can use the --debug-events option, which will emit an additional event for each failure that holds the values of primitive variables appearing in the event.
If you have added contract-wide invariants and your contracts are failing to be deployed, be aware that contract-wide invariants are checked at the end of constructors. So if your invariant doesn't hold at the end of the constructor, it will prevent it from being deployed. If you are having trouble deploying instrumented contracts with invariants, you should also read the section on external calls in invariants.
Be aware of cases where your invariant evaluation itself may cause a failure. Specifically if you are using the division opreator or calling some pure/view function which may fail under some conditions.
If scribble is generating code that doesn't compile or generating otherwise invalid code, feel free to reach out and file an issue.