Felipe, please see the 2nd edition of the criteria here: http://scholarlyoa.com/2012/11/30/criteria-for-determining-predatory-open-access-publishers-2nd-edition/
By their nature, the criteria are subjective rather than objective. Therefore, there is no specific number of criteria that must be met to be predatory. If there were an objective way to measure this that everyone could agree on, then we would rush to adopt that way. Thanks.
