Cleanest airBnB I've stayed in so far. Location is right in the middle of the most touristic area. This place is run by a company called "Prague Days", not by an individual. There are some pros an cons :
Pros :
Very quick response
Very detailed check-in instructions
Useful notes scattered in the apartment (they know what guests are up to)
Cons :
Automated messages
Requirement to sign a lease contract online on a separate website