Got a lot of NES and SNES stuff recently that has some real good titles, but some are covered in these weird white spots, the worst of em being a copy of bartman. Image here: Click image for larger version. 

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Theyre usually somewhat hardened but scrape off like chalk. I've definitely gotten carts on multiple consoles (but usually NES) like this before so its hard for me to believe everyone just splashed white paint on them and it dried 20 years ago. Have you guys ever encountered any like these? If so, is this some kind of mold, and do I need to take any precautions when cleaning these inside and out, or are paint flecks on retro games really that common?