backwards= put the the cassette on the side without the deraileur/ the lever end of the skewer on the side with the deraileur. Obviously, you can't ride like this, but you can get a great idea of what you need to fix.

I tell my students all the time to not trust the centering of our fancy pants park truing stands and to flip the wheel every now and then to make sure the caliper is still telling the same tale.