Good catch. I think this one even happens in Lix as well, though I haven't played Lix in a while so I might've remembered wrong. (For diggers, I believe you can tell direction in Lix based on the direction of the "floor sweeping" animation unique to Lix. Granted, it's still perhaps more subtle than telling the direction for most other skill types.)
Floor sweeping no longer happens in D Lix. The gradual removal of terrain was a perennial source of backroutes and fiddly solutions, so Simon decided to replace it with a "driller" that removes all its terrain at once. (More controversially, the basher and miner were also changed to remove terrain all at once.)
Just occurred to me, a more subtle (and therefore less visually problematic) way may be based on which foot the blocker is tapping. Actually, maybe that already works today? I don't remember this specific detail clearly enough.
The problem with this and similar ideas is that they are
too subtle -- I don't see how new players would notice the distinction and learn that it indicates facing. (This reminds me of a discussion we had over flipped hatches -- Nepster liked reversing the sprite to indicate facing, but I disliked it because I expected it wouldn't really work for new players, so it made the level uglier for no real gain.)
