Shared Objects

I’m using a shared object to determine when a user visited my site last. According to the date of their last visit the site will have different looks. I would also like to have different looks for users, who visit for the first time and users who simply do not allow cookies (i.e. shared objects) to be stored.
Is there a way to determine whether a user is visiting for the first time or whether they simply do not allow flash to save anything to their hard disk?