Many voucher code web sites use a click-to-reveal format, which requires the web site user to click to reveal the voucher code. The action of clicking places the cookie on the website visitor's computer. In the United Kingdom, the IAB Affiliate Council under chair Matt Bailey announced regulations that stated that "Affiliates must not use a mechanism whereby users are encouraged to click to interact with content where it is unclear or confusing what the outcome will be."
Being in Australia, I’m not required to do anything by the law (although I hear talk that there may be changes around this). I don’t disclose every single Amazon link on my photography blog in a direct way but do I have a disclaimer/disclosure page on the blog. When I’m doing a ‘best seller list’ always include a disclaimer on those posts as the whole page is filled with affiliate links. I have also written numerous times on DPS about how the links to Amazon earn us money and help the site to keep growing and be free.
Once you've protected your prospecting pool, maximize your affiliate program by working with the best and leaving the rest. As the old 80/20 adage implies, most of your revenue will come from a very small percentage of your affiliates. Because it can be time-consuming to manage a larger affiliate network, consider selecting only a few companies initially, and interview them before signing them on. Affiliates are an extension of your sales force and represent your online brand, so choose partners carefully.