Do they value and help their affiliates? Some affiliate programs do an exceptional job of communicating with their affiliates, notifying them of upcoming sales, offering marketing advice or tools, offering contents and prizes during promotions and more. These types of affiliate programs are a pleasure to be a part of. Ultimate Bundles is an excellent example.
Affiliate marketing is also called "performance marketing", in reference to how sales employees are typically being compensated. Such employees are typically paid a commission for each sale they close, and sometimes are paid performance incentives for exceeding objectives. Affiliates are not employed by the advertiser whose products or services they promote, but the compensation models applied to affiliate marketing are very similar to the ones used for people in the advertisers' internal sales department.