If we're talking within the show: if the rules allow it, go for it. Teams should be allowed to pick their own morality as long as they remain lawful.
Boston Rob bribing the bus driver not to open the back door of the bus (allowed by the rules) vs. Mark & Michael hiding the tools for a task (against the rules)
While I'm certainly not a Rob 'n Ambuh fan, it was a tactic. As far as the twinnies go. James & Abba dropped the money, there was no way to mark it as theirs (as if it had been say, inside their fanny pack). While the Twinnies could have returned the money, they had no moral obligation, specially since they cleared it with production.