TBH i dont see any problem with the term unlimited. If people read the usage policy and such before paying for a service they will know exactly what they are getting. If people dont bother to read it and just agree to everything put infront of their faces then its their own fault if they run into fair usage problems.
Unfortunately, that is not true. It is common for ISPs to use unspecified restrictions on use, covered by some general language in the T&C that could mean anything or nothing.
For example, I've read the T&C for my contract with my ISP. It does not state that the service cannot be used for P2P except, perhaps, for a few hours in the middle of the night. It does not state what the monthly cap is. It does state that there aren't any limits on the service (i.e. that the service is unlimited), which is not true.