@Tuchaka I'm sorry man, but that "rating" system posted above you is bullocks. It seems we have had a great deal of bullocks on this board lately. You can't deduce a tattoo's quality down to those elements. Mostly you just need to look at clean lines and solid application. Trying to scientifically deduce it to separate elements based on "ratings" isn't going to get you anywhere. Use your judgement, read a book on art, etc etc. Tattoos are supposed to have a little bit of soul in them. They are not mechanical and they cannot be reduced to a 0-10 rating.
This was the first book I had to purchase when I was in university, I'm not saying it's bulletproof, but it'll be more advisable than the above:
http://www.amazon.com/Design-Basics-Multimedia-Edition-ArtExperience/dp/0495128457/ref=sr_1_4?ie=UTF8&qid=1395351100&sr=8-4&keywords=design+basics