Well, the only thing I put "no" for was hitting pets--although Maciamo's arguments have put me on the fence about that one.
Here's the thing: Humans are animals, therefore I see no reason why the same rules should not apply. It is merely human arrogance that makes us believe we are "better" than animals--or even the dominant species of the planet. Arguably, the dominant species is bacteria.
Eating other animals: It's what half of our teeth are for. In fact, the only logical argument I can think of against canibalism is that humans are not civilized enough to safely interact without strong taboos against eating one another...
...scratch that--we can't safely interact anyway.
I have no problem with canibalism--people try to kill each other every day, better they do it for food than for nikes.
Using products from live animals: Having already established killing animals for food as being acceptable, I can see no reason why this would be any worse.
Medical Testing: Roughly the same argument as the food one--only without the same precedents. It's about survival. A species not willing to use every means to survive will not survive--it's just that simple.
Cosmetic Testing: This one's a bit trickier...
On the surface, you could dismiss it as vanity--but it's actually a question of attracting a mate, the single most important thing and sexually reproducing species must accomplish.
There is a veritable "arms race" in sexual attraction: A woman figures out that berry juice makes her lips red, and that this makes her more attractive to males--now every other female has to catch up or be left behind.
But then someone invents lipstick--which does the same job but the effects last longer and a greater variety of colors are possible.
Now there's a better weapon in the "war to get some".
Like all wars, it eventually comes down to a question of how far you are willing to go to have the upper hand.
If killing people became attractive--and I should point out that there are some instinctual triggers which make a male who kills other males more attractive to women--would you be willing to kill to make sure your genes were passed on?
If you answered yes, you get to go to round 2...
...if not, please step aside, you've lost--but thanks for playing the "Evolution Game". We have some lovely parting gifts for you, possibly including a place in the history of an extinct species.
Luckily, the sex arms race has only progressed to torturing other types of animals so far--but with the advent of cosmetic surgery we're getting very close to harvesting tissues from dead people--and the living are only a step away after that.
On to Circuses: Humans perform in them--why not other animals? I can't imagine a bengal tiger jumping through a ring of fire feels any more degraded than the trapeeze artists above--although the clowns might have cause for grievances.
Hitting Pets: Well, I personally don't believe in using violence to discipline others...
...wait a minute, yes I do--I just don't think hitting something you wish to care for makes any sense. If you are going to keep a pet, be it human or otherwise, I think you should keep it with the goal of caring for it--not disciplining it. If the pet doesn't respect your rules enough for your tastes, send it packing.
Pets are not unlike freinds or lovers in that respect--you shouldn't try or expect them to obey you.