The good news is that study guides and simulator programs can give you a pretty good idea of what is the nature of the ideal SCJP test question in present and future accreditation exams. The bad news is that that does not mean you will automatically pass any SCJP accreditation exam you take.
If you know the type of SCJP test questions you will be encountering, you still have to know how to find the solution to the question. So whether the question is a multiple-choice question, a drag and drop question, a knowledge based question, or a performance based question, the only realistic way you will answer it properly is if you had covered the topic beforehand in your exam preparation stage.
One good tip is that in real SCJP Accreditation Exams, you may be given a range of choices to select your answer from. In some study guides, you may find you do not have that option (and yet the study guide or simulator exam still puts you under time pressure.) The point of making the study guide and simulator programs much harder than the real exams is to hone your abilities in the exam preparation stage so that when you get to the real thing, you will be able to cope much better (even when the creators of the real SCJP exam throw you a hard and fast question that you never prepared for.)
Another trend you should be prepared for is that new SCJP exams use more performance based questions now. So if you spent your exam preparation time blindly memorizing facts, you may find yourself dead in the water during crunch time.
Look for a study guide that gives explanations for the true answers so that you know why your answer was considered wrong and how you can give a better answer in a real exam.