Thats typically frowned upon by adult companies, the incentive that is most typically tested and used over the years is telling the surfer to signup, prove they have a membership and the affiliate will 'send' the surfer $10 or so.

Of course, when they are sending the surfer to a paysite that has a $3 trial and getting $40 for it, the program owner isnt to happy about it

Regards,

Lee