The scores of your placement tests are not recorded on your official UIUC academic record. They are simply made available to your academic advisor, who will discuss your placement results and your course enrollment options when you come for registration.

So it is not to your advantage to have somebody else take your placement tests for you. If you do and your score is uncharacteristically low, you could be placed in a class that’s too easy. This doesn’t necessarily mean you earn an easy A. It could mean that you waste a semester repeating your high school work, paying for a UIUC course, and not earning any academic credit for it.

On the other hand, if you have someone else take your placement tests for you and your score is higher than your actual knowledge level, you could get placed into a class which proves to be too difficult for you. Then not only will your first year grades suffer, but your self-confidence may as well.

Only you and your academic advisor are going to view your placement test results. When you sit down together to discuss which courses you ought to enroll in, the goal is to choose them so that your first year at UIUC is rewarding and successful. You won't be helping yourself if you have someone else take your placement tests for you.