Many job candidates get nervous when it's time to do references. That's understandable — references usually come at the end of the hiring process, and there's a fear something will go wrong, sending a promising job opportunity will go down in flames.
The root of this anxiety is a misperception of what references are all about. Most people think of references as a search for reasons not to hire someone. It's true that sometimes referencing uncovers a fatal flaw that scuttles a candidacy, but that's exceptionally rare. The vast majority of candidates have nothing to worry about.
What then is referencing for?
First, referencing gives the hiring manager information on how best to manage the candidate if he joins the company.
Second, referencing helps the hiring manager feel confident in her decision. That confidence will be invaluable when the candidate hits the inevitable rough patch as he comes up to speed.
Note that both of these things help the candidate. Reference checking is not something to be feared — it's beneficial because it sets the stage for a successful working relation with a future boss.
The only time candidates with a good track record should get anxious about references is if potential employers don't do them, or don't do them in a serious way. That's a sign that the hiring manager is not running a good process and makes decisions without adequate information.