Affiliate networks terms and conditions vary from network to network. What is permissible on one network may not be allowed on another.
Some networks allow you to get away with minor repercussions, others will simply close your account.
The stricter Publisher terms include:
1. The Use of Non-Publisher Owned Web Properties/Sites/Pages to Promote Advertisers. Other than paid search, publishers may only promote advertisers on Web pages/sites/properties that they, themselves, own or operate. Publishers may not place affiliate links/tracking code, nor promote Web sites that contain affiliate links/tracking code, in or on third-party: forums, message boards, blog comment areas, classified advertisement services (such as CraigsList.org), etc., unless given permission from the third-party to do so.
Thoughts: Affiliates may fall victim to this clause. Some networks allow forum posting as a means of driving affiliate trafic, some don’t. Take special care of this clause. It can lead to account closure.
2. Use of Trademarks, Service Marks, Copyrights, Brand Names, etc. Publishers may not use any advertiser trademarks, service marks, branded terms, URL, etc, in any promotional method, unless the rights-holder has given specific permission for publishers to do so.
Thoughts: Basically, vendors want affiliates to drive traffic from keywords that do not compete with their own. So yes, the vendor is looking out for their bottom line and an affiliate is required to search out for keywords that do not compete with them, add additional value. On a side note, its also important to tread the fine line of protecting your keywords from the prying eyes of the vendor, because the keyword that’s doing well for a top affiliate, may be searched out by the vendor. It would be a sad day if a winning keyword was included in the "not to be used by affiliate" list because the vendor decides to advertise that keyword for themselves in PPC.
3. Use of Tracking Technology. Publishers are given links and tracking codes that are specific to their publisher account(s) within the various affiliate networks. Publishers must abide by affiliate network rules / agreements if modifying those links. Modifications, if allowed, must also be transparent and disclosed to the advertiser.
Thoughts: Affiliates sometimes use 3rd party tracking codes to track conversions with iframes. Some networks strictly do not allow iframes. It can lead to a slap on the wrist warning, or account closure.
Because these affiliate requirements vary, be very sure to know the etiquette required and abide by them 🙂