Originally Posted by hfpop
No. I was in airplane mode during all this experiment. The original book was sideloaded manually (i.e. without the use of any software other than the OS itself).
That's why I said, IF IT WAS SIDELOADED, the .sdr remains. Long experimentation with my Kindle Touch has led me to this conclusion, that any SIDELOADED books keep the .sdr, any CLOUD books are fully removed (Except for system/thumbnails which gives your cloud book its cover.)
And Whenever I delete a book through calibre, it gets rid of the .sdr no matter what.
The why were just my own speculation.