There are a number of tricks that some unscrupilious webmasters use to trick other into effectively proiding one way links. If you do have a link exchange strategy, don't get ripped off, make sure that it is done right. Here are a number of things to watch out for when exchanging links:
An unscrupulous webmaster may invite you to exchange links. They will inform you that they have already placed a link to your site on their link page. You check, and sure enough out the link is there. You check out their homepage, it looks good - worth a link from your site.
Check that there is a clear link or path from their home page to their links pages. The path may be indirect, such as via a site map, or intermediate pages this is fine too. If there is now way for to navigate from the site's home page to its links page, then there's no way for the search engine spiders to find the links page, the link to your site will do you no good.
Some webmasters accidently omit a link to their links page, and just need a reminder. Others will do this purposefully. If the site's links page has a PageRank greater than 0,then the search engines can and do know about the links page. If its PageRank is 0, then the page may be new or it may be inaccessible to search engines. To check whether the search engines have accessed the links page previously use the "site:" directive in the search box of the search engine. An unfortunate practice amongst some uscrupulous webmasters is to publicise their linkpage and agree to put your link on a page that is not connected to their site, but if when checking the linkpage itself the link back to your site is their. In order to appear that their site is good they will then put a link on their site with anchor text such as "resources" or "links" linking to a page that doen't exist, causing an http 404 (page not found) error, leading you to believe it's temporarily down, in reality it does not exist, readers and search engine spiders can't find the link.
When exchanging links, check each new link to your site to make sure that it is a valid link that will contribute link popularity (and PageRank) to your site. When exchanging links look out for the following;
Google doesn't allow "offpage" factors to decrease ranking, for example, if a link farm or a site that's been banned by Google links to your site, this won't have a negative affect on your site, as it's a banned site there will not be any positive effects either. However, if the link is the other way pointing towards the page that's been banned by Google, there can be a negative effect on the ranking of the page with the link. Avoid including on your site any links to sites that have been banned by Google. If a site has a PageRank of 0, with perhaps the exception of new sites, there's a fair bet that it's been banned by Google. Look up the site's domain in Google uing the "site:" directive, and if nothing comes up, you know the site's been banned and it's best not to link to it.
Anchor text is the text that web users click on to link to navigate to your page. It's become important not to have all of the links to your site repeatedly using the same anchor text. search engines can interpret this as a lack of variety due to artificial link popularity, and subsequently reduces the positive influences on search rankings. Try to encourage provide a variety of the anchor text used on links to your site. When sending out link exchange invitations, change the wording of the site title and the link anchor text that you suggest in the invitation.
Aquiring text links from sites that sell them can be useful in some cases. When doing so be careful not to purchase a link from a site that will place your link on every page in their site. With so many identical links from the same IP address will raise suspicion from the search engine. Recently Google has been ignoring whole site links.
Doorway, or "advertising" or "promotional", pages and cloaking are SEO schemes used to generate a high number of links to your site. These techniques may return good results in the short term, but they are outlawed on a number of search engines. Using these techniques may cause the site to be banned from Google.
