Hey buddy. I understand your question. I'm not saying it isn't valid in a general sense, but it's not valid here. There is an inherent issue with "reviewing" pills. The fact that you're asking for advice implies that you've acquired this from a dubious source; it's usually India even if you're buying it from a white guy. There is no accurate or even relatable way to review the effectiveness of this medication from a remote location. The only thing you will ever get will be information that cannot in any way be verified.
The best anyone can say about black market Modafinil et al: There is a brisk market for this shit among working folk. There is an infrastructure behind the production of Modafinil that lends one to believe that it's being operated like a business. The stronger a business is, the more the legitimate businessman will take negatively to the presence of fake medication. This hurts their bottom line.
Most of the Modafinil is probably legitimate just using rationale and knowledge of the market. India of course is going to have less stringent quality control procedures however, so, relative to the American pharmaceutical industry, I'm sure there are more "duds" in circulation. I'm going to close this. Reddit is really a better place for the "calling all comers, what can you tell me about..." type stuff.