Trademark law, as far as I understand, is to prevent customer confusion. Customers should be able to trust their intuition on who made a given product.

Misspellings should be covered. But hostile uses should not.

Please define "hostile uses" in a way that can be interpreted by law enforcement and the courts.

If I register "facebook-sucks.com" and put a disclaimer that facebook is a registered trademark of Facebook Inc etc etc then I'm not attempting to confuse customers of facebook (btw, do "users" of facebook = "customers" of facebook?).

Therefore there is no trademark infringement and no cause for me to cease and desist.

That's different to registering "faceb00k.com" and trying to pass my site off as being facebook. That's exactly what trademark rights are there to protect. It's not the registering of the domain that is the infringement, it's the attempt to pass off my site as being facebook's. In that case, a court can order me to take down my content, and if "me" is not identifiable, then they can order my hosting provider to do the same.

Facebook itself has numerous different domains registered and its not known that some of them are facebook's registrations.

What goes under “hostile uses”? Would people be confused if I made “facebook-sucks.com”? Because if you let something like this through, Facebook has an incentive to go after things like that…

I did a bit of research on this when I started killedbygoogle.com . It’s fine to use a trademark when it is being used for criticism, parody, or other creative work. It’s not okay to use for impersonation, fraud, or other commercial purposes that mislead consumers to believe an endorsement or association with the trademark’s owner.

Trademark law is to prevent "damage" to brands, not protect customers. If a system was in place to protect the customers, it would be the customers who were deceived that sue and receive compensation, not the company owning the trademark.