Idea quality is hard to quantify. I don't really worry about the quality of the ideas until I'm choosing another project to work on.
Some people advocate using an idea validation board: http://thenextweb.com/entrepreneur/2012/10/02/the-validation... .
Lean startup method advocate measuring market demand - http://www.slideshare.net/explorics/4-tools-for-quick-market... .
I'm not sure what's best to be honest.