Especially when the selvage stitch is really, really small, and the sewer is sloppy:
And I know you're all like, why didn't you rip it out and do it again? I told you I'm a slatternly knitter! (I like to think of myself as the anti-Grumperina). Also, the only thing worse than a mis-aligned seam is a played-out selvage stitch. This seam really, really needs to hold together, so I didn't want to stretch out my selvage stitches. But mostly, I'm just lazy. And it's a sock.
I have to admit, when I saw Julia's pirate arrghyles, I regretted my decision not to make them. My socks just seemed, well, less after I saw hers. But now I love them. The pattern has been a joy to knit (even the occasional frogging, which as Julia notes, is not fun) and I like my bright colors. And all those half-balls of sock yarn left-over from previous pairs? Crazy argyles-in-waiting.
Here's the side:
and the front:
I understand from the myriad argyle patterns out there that you can join your round pretty much anywhere on the foot you want. You can carry your argyles all the way down to the toe cap, if you like, and join into a round there--you just have to sew longer side seams. I also have a pattern that knits the entire sock, top to toe, flat, with one seam from the foot up the back of the leg. I decided to knit this pair as Julia's knitting hers, as I'm not wild about long sock seams.
But I think on a future pair I might experiment with carrying the diamonds down the instep to the toe cap. I just haven't decided where to put my seams yet.