I have no problem with my fabric from Walmart. My store has many brand names on the salvage not the cardboard. I am careful to feel all fabric I buy. If it is unknown content you are taking a chance.....but I have bought some lovely curtain fabric and garmet fabric that way. There are some big hints in care instructions.
A lot of Joanns cottons are not good quality either. I go a lot by the feel here also. I have ordered fabric on line and the score is 50% on that.
No one place you buy fabric is bad or good.......its up to you to buy or not :D