All slot machines make money over time, but the payouts to the players can differ. ‘Loose’ machines pay out more than ‘tight’ machines. Gamblers (n = 1402) at Ontario slots venues were assessed using the Problem Gambling Severity Index. Their beliefs about slots were polled using the Informational Biases Scale. Problem gamblers were more likely than non-problem and at-risk gamblers to endorse the belief that ‘some slot machines keep me from winning because they are programmed to produce fewer wins than normal’. We then showed that after extensive play (60 hours), 9 out of 10 gamblers were able to correctly discriminate a ‘loose’ machine (98% payback) from a ‘tight’ machine (85% payback). Problem gamblers' assertions that there are ‘loose’ and ‘tight’ machines demonstrate a belief rooted in reality. The ability to distinguish ‘loose’ from ‘tight’ machines may be interpreted as a skill by players. Such skill, when overestimated, may lead to erroneous cognitions.