Make a decision
Mould claim versus verified moisture
One scope
A visual patch can suggest a problem but is not proof of species or health outcome.
The other scope
Moisture source, affected material and professional assessment guide corrective work.
A concrete example
A stain on a metal duct can be dirt or growth; ask to see it and find the water source. A whole-house biocide package without that evidence is a poor starting point.
Which question settles it?
Ask to see the exact location; do not approve an unsupported blanket biocide upsell.