Sure, we all have standards. My standards of good art tend toward realism. If it looks like something that I could reach out and touch, that’s pretty good. Maybe even great. This standard I apply toward paintings, drawings and digital works (motion & still). Photography is a different category, and so I tend to look for a more emotive response, something that catches a feeling or essence of something. I also apply this toward “traditional” and digital works.
Then there is the surreal, which I also enjoy, but again with a bias toward the more realistic.
To answer your questions of what makes art normal, good or great? Sorry, I’ll have to pull out that “bull$4!7” argument of subjectivity. The more people that enjoy a piece of art, the “better” or perhaps more accurately, more “popular” it is considered to be. However, popular works are generally considered to be generally less sophisticated and more of a fad than any long standing piece that reflects the human condition. Here today and gone tomorrow…A great piece of art is usually something that moves or inspires a good number of people as well as critics.
Ah, the critics…those “professionals” who know what is best for us and what we shouldn’t like because they said so. My opinion of such people tends toward the negative. I view them, as a whole, to be arrogant and out of touch. But then, I also hate lawyers…
The Mona Lisa is a great piece of art. It’s been around 500 years gaining accolades across the generations of public and critic alike. We like it. But, when I saw it hanging in the Louvre in Paris I thought it was pretty nice, but damn, I saw some “better” portraits on the gallery wall that impressed me more. And as we go back in time, works such as the bayeaux tapestry, another work considered to be great, I see more of a historical document rather than an artwork. The figures are flat and almost childish…I don’t find it to be quite as engaging…and other medieval works look almost comical.
So, I have to go back to the original point. Art is subjective. We all have our preferences and bias. A piece that is great for one may be lambasted by another. Art usually appeals to the emotions and therefore will (or should) always remain subjective. If you like it, good. If you don’t, good. Let it be.
If you want absolutes, try looking at math. 1+1=2. However, even there we find a slippery slope with fractals and their implementation into computer art…
“Mandelbrot, Julia?”
“Yes, please.”
PS If you really want to get a heated argument going, let’s discuss Bryce and Poser. 
Personally I don’t use them, but I’m not going to knock those who get enjoyment out of it. And hey, sometimes they DO make a pretty picture…