Also, the very people you don't want to partner with are the only ones who would be interested in an offer such as this.
If your writing is indeed valuable, you should start your own blog/free site network.... that is if you haven't already. Good original text is welcomed, and you wouldn't have to partner with anyone. Do you really want to chase around money from a partner? Many adult paysites, especially newer ones do not profit. So percentage wise you'll end up with nothing
On the other side, most sites think of writing as an accessory, like getting fancy new rims for a car. You can get to the store and back with the old rims just fine. In rare cases unless the text provides TRAFFIC, it's not worth it.