I've used the Wal-mart bags for 2 years. I haven't had them leak in my pail; however, they are often moist when I dump the diapers in the washer. I've always washed them on hot with my diapers and usually hang to dry. I've had mixed experiences with the quality. One bag the bottom ripped out as I was dumping the diapers in the washer. It was kind of funny! I had it long enough and it was used enough that I definitely felt I got my money's worth. The most recent one I purchased has the lining peeling away from the color. That's kind of nasty but it still functions.
I, personally, would not use these bags outside of a pail.