You must be a constructive schizophrenic. Be clear about the difference between your role as a programmer and as a tester. The tester in you must be suspicious, uncompromising, hostile, and compulsively obsessed with destroying, utterly destroying, the programmer’s software. The tester in you is your Mr. Hyde – your Incredible Hulk. He must exercise what Gruenberger calls ‘low cunning.

– Boris Beizer (in his book – Software Testing Quotes)

Do you want to advice this to your fellow programmers/developers? Lets wish for Better Software 😛