IMHO, they all do it. I've sat and watched mine cruise around their tubs and they don't do the spinning or have any of the severe signs. The male has a slight head tilt and can get a little overstimulated if he's stressed. My female hasn't showed signs since she was a little worm and I've watched her for a good 2 hours before. She doesn't wobble if food is present but as I said, the male can get overexcited and go side to side a little.

Some of my normals get very excited during feeding time as well and will vibrate or wobble their heads before a strike.

But anyway. Just from observing spiders at shows from both big and small breeders, they all shows signs of it in some form or another. It may just be a slight head tilt when they're cruising around and nothing more, or it may be full blown spinning and they lay with their heads inverted on the tub floor.

For me, I believe it's completely genetic, and regardless of how outcrossed they are(and they REALLY are very outcrossed), it's not going to go away. It's just a genetic disorder that is linked to the spider gene. If you don't like it, don't buy spiders, simple as that(the exact reason why I won't buy Caramels, EVER).