I have never had a problem with the Walmart fat quarters. I made the butterfly out of a package.
However, I did buy the 2 yard pack and used it to put a narrow trim on 20 quilt blocks. When i got to the 20th block, the 4th side, the fabric ripped on the thread line. (This is not a joke.). I had to rip off 80 trim pieces. I went to the Amish quilt shop and bought different fabric to replace it.