Most aerialists never spin the other direction. We don't get more points for spinning the other way, and if you did spin unnatural, I'd be very surprised if any judges would notice. Spinning direction when first learning is all preference, whichever way feels more comfortable is the way you twist.
On a side note, a guy on my team did a full doublefull last year on the water ramps spinning the first full to the left, and then the doublefull on the second flip to the right. It was fucking gnarly I wonder if I can find video.