I would use a not so sharp edge for lifting the bark off for the same reason you stated. Don't listen to WB

- he's got all that fancy log moving equipment and he's never seen mud. (I'm kidding there WB!) Pressure washing works well on some species but others are like you say: It only drives it deeper. I deal with mud on most logs. We try to get all that the blade will hit but often miss some. All too often the mud has some rocks and sand embeded in it.
I think Northern tool sells bark spuds and there's others that can be found on a web search. I like a long handle as it gives you more energy release due to the big mo and mass as well as providing some extra leverage. But it seems most try to take too wide a bite.
The best bark spud I've heard about was made from an old truck spring. The steel in them is hard enough to hold an edge. It was cut past half its lenght and had a wood handle (like a large knife handle) attached to the cut off end. It was sharpened sharp on one edge. This edge was used to cut scour lines so the bark would peal in strips. The end was sharpened some so it would slip under the bark to lift it off. The tool was very handy as it not only served to debark but also came in handy as a short lever for moving cants and seperating boards. I guess you could also cut a hook in the opposite side (from the sharp edge) and use it as a pickeroon. The curve also serves the same function that the offset in a broad ax does in keeping your knuckles from getting scraped while using it. I'll try to make one this winter.