Because it's on a subdomain, just forget about this one, and move on.
One bad site might not get you blacklisted, but if you make it a habit then you could be in trouble. If you find that you have been blacklisted, you can always send an email to a site owner and say, "hey... I'm a newb... I didn't know any better, but now I do."
If you make changes to a site AFTER getting listed, you better know what you're doing and why. In some situations you're probably safe, but doing it for the wrong reasons can get you into another type of trouble - something that being a newb can't get you out of.
