Stop forum spam has 4 levels
1st level is full manual, where all you need is to have enabled it. ( no api key is required ). This allows you to manually check users when viewing their profile for being reported as spammers.
2nd level automatically checks the new registration list for any possible spammers and identifies them ( takes a little time checking with stop forum spam, if you have a large registration queue )
Now the Good and Bads will indicate whether the SFS DB had a hit.
Now you will ONLY get a 'Report Spammer' option if you select either the 3rd or 4th option, because to report to Stop Forum Spam, you NEED a key.
More info without a key will just show good or bad and you can decide to ban them, delete them or reject their new member request.. whatever.
If you DO have a key, then the more info will popup and allow you to report spammer from there.
The difference between the 3rd and 4th options is that the 3rd option informs the potential member that there was a problem and points them to Stop Forum Spam to rectify the issue ( what giz' mod was essentially )...
The 4th option, just fails silently, allowing the potential spammer to 'think' they signed up, but in reality they were stiffed silently. So it might fool some bot programs...
Its your choice what level you want to use