"Costco's Hyatt code (66267) is a Costco member discount, not a Costco employee code. FlyerTalk discussion: "Costco Travel arranges negotiated rates for Costco members — this is a published membership rate, not a confidential corporate employee benefit." Costco members must show membership card at check-in, not an employee badge. The verification risk is minimal: Costco membership is easy to obtain and the card is easy to carry."

"Many -- possibly even most -- times, a hotel won't ask for proof that you are eligible for a corporate rate. Some hotels claim to check routinely, but that practice is definitely not universal."

"AAA (alt) Hyatt codes (17500 and 15985) are secondary AAA membership discount codes. AAA rates are publicly advertised membership discounts — not confidential employee benefits. FlyerTalk's dedicated 'AAA card – Do hotels check?' thread documents: 'One frequent traveler staying 1-3 hotels per week was asked for the AAA card at about 10-15% of hotels.' AAA membership cards are easy to carry and present. These alt codes share the same low-risk profile as the primary AAA Hyatt codes."