I have not found that the quality of the thread on these larger, inexpensive spools is good enough for regular sewing. My understanding is that this is thread for surgers/surging, and where quality is not as critical, perhaps? (I dunno, I don't surge... not with a machine anyway, yuk yuk...)
I bought a few of these from my LQS and was immediately disappointed when I started threading my machine for standard sewing.