It's a cbr file, and when I manually extract using WinRAR the jpg is decoded clean (and ACV reads the jpg correctly). Looking at the cbr header, it does appear to be a valid RAR 2 formatted archive.
Most likely this is a highly compressed RAR2 file, and Droid Comic Viewer doesn't have enough memory to decompress it properly. Can you try packing the same JPEG file in a RAR file without compression and see if you get noise as well?
It's not the ratio, it's the decompression algorithm. Some require a bigger memory window than the rest, and since we limit the window to 5MB (IIRC), this happens in some cases.
That's my take at least. Not a RAR expert by any stretch.