As of now they are for me. Apparently Microsoft has been developing heuristics to detect people who use inexpensive practice tests and study materials. They threaten to ban you from any further Certification or membership in their training program if you are 'caught' studying for their tests.

I've always thought the certification exams were meaningless collections of arcane--usually marketing-centered--trivia. However, in the past, I've succumbed to one pressure or another to getting a certification. I'm done now. I don't need to give Microsoft money for useless training, or for certificates that have never helped my income one bit. Especially if they plan on threatening me.