I've gotten a couple of those. I almost always load so the seams are horizontal to avoid that weird "ridge" and puckers. But definitely let the customer know that there may be problems with puckers, keeping those seams straight etc and explain what is needed to make this work well. My "rule" is that if it's the first time I just work with them and get it to work without an extra charge. If I've had that conversation with them before, and there are still problems, then I charge for the extra work. that usually either sends them to another quilter (unless they've encountered this before and run out of quilters!) or they don't make the same mistakes a 3rd time.
I had a customer that piece a back with large chunks (I think regular blocks work ok usually)of both 42" wide fabric and pieces of wideback she'd cut and stuck together. Problem was that she had grain of fabric going all different directions. I simple could not avoid puckers as it was stretching in about 5 different directions as I worked. I offered to take off the backing and re-do with wideback and only charge for the wideback, but she was good with it.