Sure, many pinkies don't file. Companies which have registered their stock w/ the SEC though like this one assume a reporting obligation. Even after falling into the pinks, they still have this responsibility. The SEC can start revocation proceedings anytime on a delinquent filer to halt trading.
Most good trading opportunities in pinkies are created by someone hyping/touting. For every winner, someone else will lose. It's a zero sum game.
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"We simply attempt to be fearful when others are greedy and to be greedy only when others are fearful."
-- Warren Buffett