stage: COLOSSEUM TOWER (0) +1

Brawl does not store a full-size image of your stage inside the stage file; it only stores a thumbnail like you see above. The blurriness is the result of enlarging the thumbnail. However, BrawlSnapshots.com lets the submitter of this stage associate a better resolution snapshot with it by clicking "Edit" and then "Pick a Different Snapshot", so bug Anonymous to do that for this stage.