I found when I have acquired a new link toward a website with the certain anchor text. The ranking for that certain anchor text will fluctuate. I assume that link with anchor text does not always help but sometime harm. What do you think? Even a quality link needs time to prove.
Based on my experience, only if an unusually high number of your links has the same link text will link text negatively affect rankings. It's very rare that a single inbound link will "harm" rankings.
Definitely Anchor text has both credits and discredits. These two factors are based on the quality of the page it is residing on and the number of times people reached via that link. Clicks are one of the most important factor considered in keyword ranking to a webpage's anchor text score.
Yes, the abnormal rise of same text links are considered to be spam. This mostly achieved by participating in link exchange schemes which is against to Google's webmaster guidelines.
I find that an out of character link will lead to dancing on sites that have a high established profile for a niche. If you have a baseball web site and for years your links all come that niche and then I get a few links from high PR (non-news related; out of niche) sites, I will dance for 2 to three days.
Too much of anything is bad. Dances might happen because of the constant PR shuffling around in the sites that you have links from. Other sites losing or gaining PR will affect this too, so you can't just assume it's your links that are the reason for the fluctuations.