I don't think there are many.What are some known precedents from previous similar cases?
Sherman got out of a 4 game suspension by arguing the testing procedure wasn't followed correctly. That was for PEDs, though, not under the substance abuse policy.
As has been noted many times, we aren't privy to the elapsed time in all cases, since news of failed tests/appeals aren't always leaded. The NFL doesn't make official announcement until they have made a decision.
Reports have said that the NFL has never negated a positive test based on the "2nd hand smoke" argument, but the fact is if a player was successful in his appeal (and the news of the failed test/appeal hadn't leaked), we'd never know. So, in theory, players could have successfully appealed a suspension many times, and we just don't know.