Scratch files left behind by arcpy.sa.Con

Figured out the issue. Part of the problem was that I reduced the scope of my real problem too much when I asked the question. Had some good help from Barbara S. @ ESRI on this.

The soundbite is that arcpy.env.mask gets applied before actually executing the function, creating new grids.

Two of the inputs to my Con() are raster objects (elv, rCtype). Because these objects had a larger spatial extent than I needed for the output from the Con(), I had set arcpy.env.mask and arcpy.env.extent to limit the spatial footprint of the output. I thought this would simply control which cells were accessed in the application of the Con(). What apparently is happening is that prior to processing the Con(), a reduced-footprint derivative of each of the grids was being created and used in place of my original raster inputs. These grids are not temporary and persist on the disk. In addition, because of the dynamic way in which these grids are generated, there was no variable or way to reference these new grids. Bit of a bummer since cleaning these up is a hassle (really have to leave the python session altogether).

Seems like one robust solution is to explicitly pre-filter the spatial footprint of the input grids and the delete them when the Con() is done. Actually writing out a new grid, instead of constraining data read into the Con() function, seems pretty wasteful. Maybe it allows arcpy.sa functions to better scale to very large rasters. I'm wondering if this pre-extraction must occur I should run in the "in_memory" workspace and then explicitly save stuff out. I assumed that running local to the input grids would be fastest. I'll run some tests and post to a separate question for that, I guess.

Update

Turns out that the clean up of by-products created from arcpy.env.mask varies depending on what you use for your mask. I haven't tested too many options, but my use case relied on a fgdb featureclass. There was no leftover data when I used a grid for the mask.