If one is masquerading as a black belt in today’s BJJ world, chances are sooner or later they’re going to get exposed. There are lineages that can be traced back and when one pretends they have earned a black belt when they have not, they not only insult all the teachers in that lineage, but any student who might study under the imposter.
Ruben Alvarez of Black House MMA (Miami Beach) recently exposed a charlatan in his school and handled it perfectly, making the perpetrator remove the belt and leave his academy while letting him know if he should ever return it would be as a white belt. Alvarez was upset, and with good reason, but he controlled himself and the fraud was able to walk away on his on two feet.
https://youtu.be/N-MHpIqr06E