In general, it is poor preparation to give students tests that are found online, however, some of these tests may come from official AP resources. With APs, your teachers are trying to give you the most authentic experience to best prepare you for the real exam. It’s not “cheating” per se but it is pushing unethical. Ask yourself this: are you going online for help learning/understanding the material, or are you trying to do well on the test? If you’re just trying for a better grade, you’re stepping into unethical territory. Some of the materials you’re finding online are not intended for student consumption or are there illegally. If you want extra resources, try publications like Barron’s books that are both legal and intended for students. It’s not a good practice anyway, because you’re giving yourself an inflated sense of your abilities that won’t serve you for the real exam. You also might be skewing the data for your teachers if your class test grades are better than your AP exams.