Carpet square issues

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Some of the spots are grease but most of the other spots are food/drink. The janitor tried to get them out before i got there and i am thinking thats 'part of the issue. I never had any problem before but these light gray color squares are being tough. I did spray them with a DS spotter and also i went back and tried hydrox on them but that tended to leave a white color where ever i spot cleaned.