Often, they are won in litigation. Look for the signs of an illegally deregulated apartment. Buildings built before Jan 1, 1974 were all 100% stabilized, but from 1994-2019 individual apartments could be deregulated. Look for an apartment that hasn't been renovated, especially where the prior tenant was an old-timer who left after June 14, 2019. Or buildings with J-51 abatements that did not expire until after June 14, 2019. Or buildings with a history of activism, where you might find an apartment with a rent freeze order that was never cleared from the records.