As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
DIRTY SOCK SMELL ON START OF APU AND LINGERS WITH APU RUNNING. ODOR ALSO REPORTED DURING APU START ON ARRIVAL, ALONG WITH APU START AT PREV STATION. FOUND DE-ICE FLUID AROUND APU INLET. REF ODI LOG 0637846 FOR CORRECTIVE ACTION. (LP# 6114270)