Don't worry about culling them as you go, use an image grading app to score each sub, saves a lot of time. SGP has a standalone image grader. It will run the contents of a file and sub files, and break them down into filter groups, computing a score and calculating the variance from the mean. I find it very helpful, with no need to eye ball each sub. The app can rename the bad subs for easy deletion or move into another file.
http://www.mainsequencesoftware.com/...ts/ImageGrader