you're mixing your frames of reference....
The simulated 'moisture' would exist within the simulated universe using simulated water and simulated fabric (for example).
Within the simulation, that fabric would be just as moist as a piece of cloth left out in the rain in our universe.
you can't mix your frames of reference.
It has, if it has to be "moisture" and also to be "just as real".
Else, you can define as "moisture" any parameter in the simulation (since it can be "whatever it likes").
E.g. the property of being "alive" in Conways Game of Life.
In what sense will that be a simulation of "moisture" and "just as real" inside the simulation as moisture is to us?