So I placed the Basically A House lot down and moved in a family to find...the tile floors were shiny. This isn't a base game thing, right? I don't remember it. In Base Game + All other expansions, only certain textures were shiny- like the flat black leather texture. But this is a stone texture, and the shine is consistent across the floor rather than across individual pieces.
Either way, base game or not, the floors are very odd:
-If cloned, they stay shiny
-If placed from the catalog, they are not shiny
-They can be designed just fine and keep their shinyness
-The shinyness is not connected to the design, as copying the design to other floors doesn't make them shiny.
(Note that the tiles closer to the camera in the second shot are not shiny, despite being the same floor with the same design)
There are no buttons anywhere to enable this, "Help" doesn't bring up any cheats that might do it, there's no object to do it. The shine is a little extreme but it'd be nice to have for any floor you wanted.