No, it's not. Opinions are just an idea without any proof or evidence, and they can be disproved anytime.What makes good animation? Who dictates what good animation is? I took a flash animation class. At what point am I qualified to deem whether artwork is good or not?
These are all questions you can't answer because it's all opinion.
Animation is composed of many elements, many characteristcs. There are these 12 basic principles of animation that your animation should follow to be at least acceptable. This is a start. The other characteristcs are usually related to the movement, drawing and details. They can be better analysed by those who knows the principles of drawing. Following basic physics rules for exemple are something that improves the movement of your animation.
The rest, I don't know how to explain well, because I'm not good at it.
Now, no matter what you say, it's not up to opinions, it never was. You can keep telling yourself that, but nothing is. Reality is one and only, there's a truth about anything.If every opinion was true, reality wouldn't make sense, because we would have countless truths contradicting each other.
You're mistaking characteristcs with taste.