If you're using name.com's DNS, then they've basically got a wildcard subdomain that points to a spammy domain-parked page.
So, say you have valid records for .yourdomain.com and www.yourdomain.com. Those two hosts will resolve as you would expect them, but *.yourdomain.com will resolve to a spam page.
Wow, that's pretty evil. I definitely won't be using name.com (I've been happy with Dreamhost as a registrar for years anyway, but would be interested in trying someone else in the future). Thanks for the heads up.
So, say you have valid records for .yourdomain.com and www.yourdomain.com. Those two hosts will resolve as you would expect them, but *.yourdomain.com will resolve to a spam page.