ya the best answer is by asking them and telling them which payment method that you would like for your convenience.because sometimes checks can be such a pain in the ass if you're an international affiliate.i know most product owner prefer to pay via paypal for international affiliate because it is instantly.

instead if by checks it would take almost 1 month for it to arrived at your door step and then you would need to wait 1 more month for the check to be cleared by your local banks.there is also risk that the check might get stolen or did not arrived to your address.