It’s completely dishonest. It’s pretending there’s commerce or life where there ain’t. Pop-up shops actually exist, albeit for short leases. The idea of a short lease, while probably not needed when times were good, is inspired. It allows entrepreneurs of all kinds to try out ideas without commiting vast amounts of capital to a years long lease. Several of Dublin’s pop-up businesses have become going concerns.
A lot of empty buildings hurts the city and the building’s owners. Encouraging new businesses is a really good idea. I’ve often wondered why city governments don’t offer to negotiate with the building’s owner for a reduced rent and the city could subsidize part of it for a short time.
Hiding the problem with graphics posters in the windows doesn’t seem like a very good solution.
The dog in front of the fake butcher shop looks disappointed that it’s not real. 
Window posters are cheaper - it’s a one-off cost. Besides, This and incentives to encourage business are not mutually exclusive.
Just to reiterate, this is not something they invented for the G8