Socks doesn't like going to the bathroom in a place until she's familiar with it, which means that she's smelled everything in it at least a billion times. We had that problem when she first came to live with us but we didn't realize the pattern; it seemed instead like she wouldn't poo until she found other dog poo. However, later, when I got the Springer and started taking her to the reservoir, she started going there after she was familiar with it.
What's difficult about it is that she may have to go really bad and whine about it a lot, but she still won't go until she's sniffed very thoroughly. That's what was happening last night. She'd been taken for several walks, after a day already filled with exercise and excitement, and still wouldn't go, but she kept complaining. I took her out for almost forty-five minutes (long enough for my knee, which was feeling better than it had in days, to start aching again) but still no luck.
Fortunately Siobhan took her out one more time and while she didn't do anything I hadn't done, it worked. Maybe her need to go got to a critical threshold, or her familiarity with the smells reached a breaking point, but suddenly and quite quickly she was willing to go. After that, she passed out and barely moved all night. Thank the stars, it would have been an awful night otherwise.