For me:
-70% of Wal-mart's imports come from China, which considering how much stuff is imported kind of scares me.
-Some of the factories that make stuff for Wal-Mart, in China, use prison labor.
-To me people's buying power (increased) by shopping at Wal-Mart is offset by the jobs lost. The vast majority of the people who shop there are lower and middle class (which is most of America anyway). A lot of these people have hurt themselves because their jobs get shipped overseas due to the stuff that they buy at Wal-Mart.
-If you buy something from Joe's hardware store on Main St, Joe gets the profit on the products he sells. So then he might get Bob the carpenter to put an addition on their house; thus the money stays in the community. With Wal-Mart it goes to Bentonville, AR, and 5 of the 10 richest people in the US (IIRC, Walton's are 5 of the 10).
I don't know enough to get into their HR issues in this country, but there have been many. I generally try to avoid shopping there, but sometimes it is inevitable. I have tried cutting down on my trips to Sam's Club as well.