The free stuff isn't the whole issue either. In mainstream you can expect vastly better ratios depending on the product you are promoting.
Heres my main mainstream sponsor since oct .... seriously we haven't seen ratios like this in adult since 1996! Its normal to see ratios of 1:5k or worse now even on SE traffic in adult.
Why would I bother with adult when I am seeing these results... and within a year of first starting !!!