I’ve now seen four listings where the HO is either explicitly asking for a house swap, rather than just a sitter, or where they give the impression that’s what they want.
“We’re sitters too and would love to look after your furbabies while you explore our area..”
I’ve no idea if this is allowed. I suppose there’s no reason why not. I’m posting about it only because most of the listings of this type I’ve seen are confusing: They hint strongly that they want a swap, but don’t make it clear if this is all they’re interested in. I’ve ducked out of applying for a couple because I couldn’t face the hassle of submitting a test-the-water “application” just to try to clarify..
But is this even allowed? After all, there are other platforms for house-swappers..
I saw one saying they would like to swap. Multiple dates listed. In Switzerland. I could be there during one set of dates and correspondingly my home would be empty. I reached out and enquired but as I suspected Australia was too far away 
I guess no harm in trying.
@DieFledermaus, what a curious topic!
We’ve met pet parents that are dual members of THS. A subset of them mentioned to us that they sometimes concurrently housesit elsewhere while own pets are being housesit. But most noted that concurrent housesit is just too difficult - both in terms of finding a match and pragmatic risk.
Perhaps such pet parents will find a match. No idea. But it must narrow the pool of applicants a whole lot. Suspect disappointment beckons.
I reported one a while ago and I was told it is allowed. Members can arrange a house swap if they wish. So I guess that would involve a lot of swapping of photos and details yourself to make it work.
Sorry! I am duly crushed. (I just didn’t know where else to ask the question.)