Nothing is worse than having weak references destroy opportunities for you. This can reflect poorly on you. The person you chose as a reference, sounds immature over the telephone, or reveals they are a friend or relative. Any combination of these factors can leave an uncertain or uneasy feeling with the company doing an inquiry. The person you chose as a reference is not easily available or does not make it a priority in their schedule to be available.
Companies have limited time to set aside to perform reference checking.
An unavailable reference will leave a negative feeling, especially if the company has had to chase down your reference. The person you chose as a reference has not worked with you in years, or never really worked with you directly, rather, he interfaced with another development team. This leaves a company doing an inquiry wondering why you can't provide references that worked directly with you. Basic Guidelines for Dealing with Your References Companies generally seek three references. I recommend having a fourth reference as back up.