How could you tell whether you Bookmaker/runner is trustworthy or dubious?

It is hard to differentiate as it is only by betting over a period of time before you could tell.but common signs includes setting a "high minimum bet" for instance minimum $5k unless the person is really someone whom you known for a very long time and you feel you could trust him chances are when you win he is no-where to be found.common flimsy excuses given includes bookie run away or bookie got arrested.Another common sign is they only open a few matches for punters to bet.come to think about it if he is really a bookmaker why should he restrict the no. of matches available for bets chances are those are the games he is confident of and would accept all those bets which is opossing him.