I'm new to this site. It looks like it is a great resource.
I've had several Pfaffs and have a Creative Vision right now. I think you should try it both ways to see if it makes a difference. I've decided that it does. It may just be my aging eyes, but I think satin stitches/embroidery look smoother when it is on the 'right' way.
I was told to put the spool on, right-side up, which made no sense until I realized that the brand label would be on top or the writing on the edges would be readable. (A bit of a 'duh' moment.) Since I have had spools that were wound the other way or don't have a label any more, it is easier just to make sure the thread is winding onto the spool clockwise, looks like a 6 from above, the same direction the thread needs to be when putting a bobbin in the bobbin case.
If the thread doesn't feed smoothly and gets tangled, even with a large thread-cap, flipping the spool over over fixes it.
If it is METALLIC thread, it does make a difference (which made me realize that it might make a difference with other threads.) If metallic thread is sitting the wrong way, it will twist and make kinks in the thread, causing all kinds of problems. Sliver has the same problem. The 'right' way may be the wrong way for metallics. Test it to make sure.
My dealer found that putting Jenny Haskin's new metallic mini-cones upside down on cone holders keeps it peeling off smoothly. It twisted and kinked terribly and broke a lot the other way.
Kathleen in Portland, Oregon