I think I have a reasonable understanding of how page rank works and the importance of anchor text, however I have started to wonder about how google might treat links with different sets of anchor text. For example, I get a whole lot of links and take top 10 for "keyword 1". I then keep these links in place and get a whole lot of links for the unrelated term "keyword 2" pointing to the same page. Obviously you will start to rise in the serps for keyword 2 but will there be any lowering for keyword 1? Might you drop to page 2 for example, all other things being equal. Any thoughts on this?
There is a complete possibility that you start ranking on the second keyword, should the competitors on the keyword2 are not very aggressive at the Link Popularity or any other Marketing tactics. This would also not effect the keyword1 ranking, unless you make alteration to the website. However, there would always be the risk of Google being informed of an unrelated site' ranking by any of the competitors, there. BTW what could make anybody, consider a not related keyword for such an expensive and useful marketing initiative.
Not really thinking anyone would want to start ranking on unrelated terms. Just trying to abstract away fom common practice to get a feel for peoples view on the algorithm. Insights could lead to implications on what level of (related) diversity you should give your anchor texts in a link campaign
you should not be using any unrelated keywords for linking with anchor text. rather you need to use related but different set of keywords. google like to see variations in anchor text linking. since they use word association technology, you will do better if you use few relavant keywords for anchor texts. for example, if you are selling "sports car" then you can use keywords like sports cars, buy sports car, used sports cars, etc. same keyword but different variations.
No, it will not affect keyword 1 but to really maximize your goals start seperate subpages for each, new content = better rankings in every way.
If you have all your links sporting the same anchor text, Google will smell a rat. Variety is important, for a site that is being linked to naturally will always have varied anchors. It will also help you rank for more terms which will bring their share of traffic..