Writable shared folders in NetScan

I would like to know, if NetScan indicates that a folder is writable - how confident is this?
Let me explain: I see shared folder security as writable, Everyone. I see shared folders as writable. Is this tested by Netscan? For example, does it create a temporary file on each share to confirm this or is this simply because of the displayed permissions? My boss would like me to sweep each folder manually to confirm if I can write to each of these folders, but I figure if the product already displays this then why do I need to also try to write to these folders?

The writability is tested by creating a temporary file in each share. If that succeeds, the share is shown as writable.

Unless there is a third-party system software that alters the behaviour of system calls, I'd say the confidence is 100% that the user running the Network Scanner can write into those shares.