Holding on to Mayor-ships is much harder than just checking into multiple different venues to get badges and should therefore be considered as a major part of the grading criteria. Plus, using "Only Badges" as a grading criteria guarantees the people that have been using foursquare the longest top scores due to the fact that some of the badges that are event specific are no longer available to everyone. As a result the current grading system will never give a new foursquare user an chance to get a Top 100 score.