I tend to finish shows that I either like a hell of a lot, or completely loathe. I won't hesitate to drop a show if I find it painfully mediocre. I try not to juge others for their taste, I consistently fail in this task.
My rating system is based on my own subjective enjoyment of a show, if there are objective things that should count towards the rating, I'll often post about those things in the relevant thread on the forum and adjust the score accordingly.
Thanks for reading, now listen to Noa