When there are cars around, I always stop. I expect them to follow the law. They have the right to expect me to follow the law. If a light won't change for me, I treat it as a four-way stop (which is the law for defective lights).

I confess that when there is absolutely no traffic around (including behind me), I treat stop signs and red lights as yield signs. But I slow way, way down, enough to make sure there really is no traffic. This usually only happens at 5:00 a.m.