I've posed this question with FinCEN and been told a SAR is required if the bank has adequate information to provide on the SAR that would identify the subject; so it is somewhat subjective. There is also guidance in an old FinCEN review (I believe) that acknowledges that most times a name is associated with a scam, it's a fictitious name. I believe that if you believe you have the real name of a subject, you should report, even if that's all you have. If you just have a name that's listed as the "President" of a sweepstakes or something, you can probably document why you don't have a true subject so you don't meet the filing threshold. We often don't file these cases.
The safest course would be to just file though- choosing not to in a subjective area like this opens you up to more criticism from examiners. I also think it's worthwhile to consult FinCEN yourself if you want to rely on the guidance I referred to. It's not published, so you'd want your own record, and who knows if they've changed their thinking since then?