Sitters are encouraged to review the dog. We're given 1-5 stars to choose, and to write anything we think is useful to know about the dog. Rover says the information is never shared with anyone. They present it as making a note to ourselves for future stays.
But, in one place they say we can write anything we feel Rover should know about. I assume they would review any sitter "reviews" (of a dog) if that dog came to their attention for whatever reason. For example, if we can't keep a dog, we're supposed to call Rover to help find another sitter. I assume Rover staff would review that dog's feedback (from other sitters) to find the right sitter, or to "sell" the proposal to an apprehensive sitter.
Some sitters want the ability to publicly evaluate dogs (and maybe the owners too). They might say it should be limited to sitter-eyes only. But, there's no way to enforce that. So, for all practical purposes it would be public. It kind of makes sense. Don't Uber drivers rate their customers?
But, I think it would generate a lot of hard feelings and put Rover in the middle to arbitrate complaints, be perceived as "taking sides." For example, I'm never too trusting of dogs I don't know. If any damage occurred I would blame myself for trusting the dog more than I should have. (I don't know how rare my view is, but I always thought it was widely held at some time in the past.). So, if there were widely differing views like that, the dog (or owner) could become the target of criticism that some (me at least) would say isn't deserved. (Then you'd have hard feelings and Rover's judgement put on public display -- instead of conducted privately when needed, when a dog comes to their attention.).
It's too bad. It would make a lot of sense to share perceptions. But, I just see a lot of trouble arising from it.
If there's really a need for something like this, what I see happening is someone creating a "rate-your-rov.er" website where sitters could voluntarily rate a dog, or check to see if that dog has become the target of controversy. It could all be anonymous (which would diminish the reliability of the info even more than what I described above). But, that could be better than nothing for those who feel it would be valuable. It wouldn't be hard to create a site like that. The functionality would be very limited. It could be a blog where you could search for blog titles containing a Rover user's name and/or dog name. Search for tags of nearby cities. (It wouldn't have to be a custom database insert/search web "face". It could be a commonly-available blog template.).