I worked for Costco for almost a year. I won't speak for the company as a whole but my location sucked ass. The upper management were all incompetent egotistical morons who would bend over backwards to suck off the most brain damage and entitled customers. Blatant favoritism and sexism of the staff. Inconsistently applied punishments.
I liked most of my coworkers and floor leads but the upper management were some of the worst I have ever worked for in my entire life.