I think the best way I can answer this is to say that if you follow the terms and conditions of the trial offer you should have no issues with receiving credit. This includes not using incorrect information and cancelling within the allowed amount of time. Cancelling an offer before the trial period will not necessarily nulify your credit. However, if you do the offer and wait for credit and then cancel you can have your credits revoked. I would agree that you should only try offers you are interested in. If you try and offer and find that it is not for you then you are allowed to cancel. Just know that the advertiser always has the discretion to revoke credits if they feel you haven't given the offer a "whole hearted try" and only signed up to get the credit.