Am I crazy.

[Celestria]

On a pet group on fb I have seen a terrier advertised for rehoming. For a month. It's four years old and no one seems to want it because it's not house trained.

Every time I see her appear I feel sadder and sadder for her. I'm in a permanent house now. With a totally secure high fences back garden and home all day. I have four kids and two cats.

Am I nuts for considering her? Can an older dog be house trained?

You can house train an older dog but you would need to find out about whether she is cat friendly - I have a terrier and he could not possibly live with a cat .

Have you any experience with dogs, particularly with ones that have issues such as not being house trained?

I suspect that 'not house trained' means it's an outside dog, so quite possibly not used to DC or cats (and terriers do tend to chase cats unless socialised really well with them).
Or it could mean a medical problem that is expensive and ongoing.

What i would do is look up a terrier rescue and post the details in the group, urging the current owner to get in touch with them.

The cats would be the deal breaker.

Is the dog with a rescue or is straight from a home? I'm assuming home but might have misinterpreted your post.

The problem with taking a dog straight out of a home with no rescue assessment is that they could tell you anything you want to hear to get you to take her - "cat friendly? sure no problem!" People can and do lie in these situations so it is a big risk to try it with no independent assessment having taken place and nowhere safe and appropriate lined up to take her if it doesn't work out with your children or cats.