What you can safely see
Look at the removable filter, the louvres and the accessible airflow opening with the unit switched off. Take a photo if you need to compare the condition later or send it to a technician.
Why the visible edge is not the whole system
The indoor head contains a filter, coil, fan barrel, drain pan and housing. A clean-looking front cover or filter does not show the condition of every accessible internal component.
Avoid the quick chemical fix
Household sprays and excess water can damage surfaces or electronics when used in the wrong place. Controlled cleaning, containment and a final test are part of the professional process when deeper access is needed.
The practical takeaway
Visible buildup is a reason to inspect and clean appropriately. It is not a reason to make unsupported claims from a photo.