At lincraft (the large craft store in Australia) they always rip my fabric, and ALWAYS get it wrong by 1-5 inches. I guess because all the part-time workers are teenagers who know nothing about fabric and are just working there by chance. I always base it that if I'm going for the cheaper (like 50% cheaper) fabric from lincraft I use it in-unimportant projects, and keep the quality LQS stuff for when I'm putting a lot of effort in.
I wouldn't mind them ripping if they could just get it right or add extra but oh well