There isn't and there shouldn't be. Trust should be something they (the someone you speak of) should take personal and not rely on the forum for suggestions. It isn't a must to customize your trustlist in a day. lets say they spend minimum 20mins browsing through the marketplace board, there's nothing wrong in using two weeks or even more to customize your list i.e taking note of at least one trustable user daily until you get at least 10 to make a perfect list and they can always adjust the list to their taste. You don't even have to trade with them, their past/present records of forum activeness (scam busting) can be used for your judgement to determine if they're worthy to be included on your custom trust list and if they turn out to be the opposite you exclude them.