I thought I'd be able to go a few days without (or at any rate only bathing from the ears down): I cut my hair to ~1/8 inch the day before the surgery, and scrubbed myself thoroughly in the shower that morning. And I had worn a full beard for a decade or more, ending in 2002; surely I could go a week again without shaving.
Wrong. I did the ears-down thing yesterday just fine. But when I woke up this morning my first thought was Oh my god, I need to wash my hair! And shave! I went ahead and had breakfast anyway, on the theory that I'd get used to it. Not.
A wonderful lady once wrote me a poem listing my virtues, among them hygenic (I don't recall right off what she rhymed it with). So I suppose there are worse habits. But I really am surprised by my inability to put up with being just a little grungy for a few days.