I'm using a system that compares different books with each other. I tried this about a year ago using BookMaker as the book. It seemed BM was a sharp book since their lines were 50 points or worse for certain matches. For example, they had one team at -200 while other books had that team at -150. I thought they were sharp but it seems that they were just handing out lines that were worse.
This time I'm using multiple books to determine if a team has an edge. This Brazilian league seems to work the best for this so far.