Originally Posted by dunster

One misconception I hear a lot is that seam allowance doesn't matter, as long as you're consistent. (That only works with a very limited set of patterns. The rest are designed for a 1/4" seam allowance.) Another is the complaint that patterns should be designed for 1/4" instead of for a scant 1/4". (They are designed for 1/4". The scant comes in because fabrics and threads have different thickness, which has to be taken into account.)

Another misconception is that all quilt store fabric is good and all bargain store fabric is bad.

And then there are many, many misconceptions concerning copyright.