Thank you for your suggestions thus far!
The photos seem legit. These are all modest places. I haven't seen any common to vrbo and booking.com. If they're not on both, are they necessarily scams?
Not in Mestre, not even looking at north of the station. The maps, descriptions and directions to get there indicate right in the heart. I agree with wanting at least one review. Lots have reviews, some have mostly reviews in French and Italian. I am fairly fluent in French and can get by on my rusty Italian (taken 20 years ago). If the reviews were in broken English, I'd be more sceptical - not sure it would be a legit basis!
I've used vrbo in Maui, SFO, London and Paris all with excellent experiences.