Telling your people your competition sucks isn't unethical, you're just making them aware that you can provide them with more value. If you can't live up to your claims, you'll feel the backlash.

I can see that using Mechanical Turk could be unethical for certain sites (e.g: dating sites), but it could also be pretty useful, and was something I hadn't thought of at least.

Also, I don't see how your complaint about #5 applies to blogs but not twitter or facebook sites.