Rule #1 is DON'T degrade your present or past employers. If you're explaining why you left a company or why you are currently considering a change, give them the benefit of the doubt and be charitable regarding their shortcomings. Go ahead and point out problems you've encountered, but offer possible solutions you explored and were unable to enact despite your best efforts.If you appear to have given up on a situation without working for change from within, it really says more about you than does about the company. If you are currently unemployed for any reason other than economic layoff, be very careful not to sound bitter or to over-explain. Give a concise explanation, giving yourself the benefit of any doubt and trust that your background and personality will carry the interview.