Tentative rating scale:
5 stars --> These are true masterpieces. They have that something extra which makes them outshine all others.
4.5 stars --> These are pretty damn close to perfect. They're absolutely brilliant, but not quite as affecting as something rated with 5 stars.
4 stars --> Titles that I greatly enjoyed watching. These gave me everything I could have been looking for, but nothing more.
3.5 stars --> Above average, but not by much. These were still very enjoyable, but didn't have much that I found to be particularly special.
3 stars --> Average. I honestly enjoyed watching these titles, but perhaps would rather have been watching something else somewhere in the back of my mind.
2.5 stars --> The bad qualities outweigh the good in these ones, but not by so much that I had much difficulty watching. These are the anime I watched when I was bored and was waiting for something new to air.
2 stars --> These were difficult to watch. Not even close to average, these are the titles that I didn't want to finish once I started, but would have a complex about dropping (because I never like to drop a series).
1 star --> I generally don't use 1.5 or 0.5 star ratings, because 1 star is able to sum up all three of the lowest ratings: don't watch this. Stay away.