So after what seems like aaages, I think Dexter is finally starting to understand the whole house training thing. We're still not there yet, but up until about a week ago he had no connection between needing to go and going outside. He would go if we took him out, but if he was inside and needed to go, he'd just go, making no attempt to communicate, even though I've been trying to teach him to paw at the door when we go outside. But all of a sudden I think the penny's dropped and he's now walking up to the door when he needs to go, he's done this probably 4 or 5 times now in the last week. We're still taking him out regularly, but any time he voluntarily 'asks' to go out is greatly rewarded just to drive the point home. I think we still have a while to go, as we are still having an accident hear and there, but it's sooo much better compared to what it was. I was beginning to think we would never get there! This is at least given me a bit of hope that one day he will eventually get there.
Once 'success' has been achieved, eg: your dog is consistently asking to go out and is no longer having any accidents... how long do you need to keep reinforcing the behaviour until your dog is 'reliable' and can be trusted inside while you're out? I'm prepared to not really be able to trust him fully for a long time, if ever. I've read that dachshunds aren't the most reliable when it comes to house training, and one of my OH's work colleagues has one and said it's not 100% and I'm pretty sure it's a few years old.