jakebohall - 4:00 pm on Sep 3, 2013 (gmt 0)
Deeper... Using commercial terms in your anchor text theoretically increases your chance of an unnatural link penalty.
I do not know of any rules of thumb that state when it is okay to use keyword specific anchor text... I believe the biggest question to ask yourself is intent. If it is for SEO, you should avoid it unless it is strongly defensible. If it is for usability, that should be okay. My standing recommendation to webmasters is to leverage their domain name as the anchor text so as to avoid accusations of manipulating rankings for certain terms.