you can post any number of muddy pics, and I can post any number of clean pics, it isn't going to change anything. We're just going to have to accept thatit's different for some people than others, it would be slightly suspect even if everyone experienced everything in exactly the same way.
If i could tell you what it is that i do that means i don't get muddy - i would, but I dont' know, i just DON'T....
Admittedly the front of my shins were wet today (similar to jiggerypokery's pic), not muddy, and only as wet as, say, my face was, so entirely attributable to forward motion incident upon raindrops en route from cloud to earth.
oh, and: trike - whole different kettleof fish. arms much closer to ground! specially if USS? and also TWO front wheels so point about the spray having to splay out to be incident on anything other than the downtube doesn't apply - your arms are directly behind the wheels aren't they?