Testing of Expert Advisor

Before putting out my hard earned money for any product, I would want to be sure that what I am buying is in fact going to do all that it is advertised to do. If I made a purchase of a forex expert advisor for managed accounts would it be a fair test to just perform a forward-test of the product or is there a live forward-test that can be done to ensure the numbers produced are not doctored in a way as to create the illusion of a superior performing product? These tests need to be made available prior to purchase.