I have had a hard time being able to answer a question. Which I thought would be simple to ask and have answered. "Does this file service have an auditing function?". Noone is really forthcoming with an answer. It's one thing to take a SAMBA file server that is using a cloud service for any type of back or synchronization and manually add the file_audit parameters to the configuration.
The problem is that those same services have an online service too. So even if you have the local auditing turned on, it really needs to become an integrated logging and audting function that is driven, controlled and reported via their centralized service.
They all have marketing hype related to their new features, usually social network integration. Heck, if they are going to open the authentication floodgates, they better get seriously competent in getting their audit trail in order!