I know what you mean... we had a lab/dachshund mix that had absolutely no health problems but always peed all over! We called her "sooner dog" because she'd no sooner come in from outside and pee on the carpet!

We'd have her out on her lead all afternoon in the summer - she loved it, and had EVERY opportunity to go at any time during the day. When did she go? The minute we let her back in the house!

I honestly think she was seriously abused before she found her way into our home and this was a remnant of her horrible past. We were never able to break her of it. It DID get better when we walked her reguarly - as soon as I crawled out of bed, again at lunch (thankfully I worked close enough to do that) as soon as the kids got home from school, at dinnertime and again right before bed. That was 5 times daily at a fairly consistant time. She KNEW that we weren't going to forget her and leave her for too many hours before she could go again - this is where I think the first people were at fault... I don't think they ever let her out properly or faithfully - and then I think they would beat her if she did anything in the house.

Do you know her history of her previous owners? It could be something similar to what we went through with Sammy.