Agreed completely.
I shared some of my thoughts here: https://www.reddit.com/r/cars/comments/3yqjem/truth_or_myth_never_buy_exrental_vehicles_aka/
It’s probably less risky than buying from a private seller/dealer, unless the private seller treated it like a baby (in which case you will be paying a hefty premium). Issues due to misuse will show up right away.
TL;DR: They should have a binder full of Maintenance records. Cross check them. Look for issues and walk away if there are any you can’t fix within budget.