What is the best way of getting muck out of bricks?
best way i found so far is simply using a plastic-toothpick (wooden ones should also do the job). just get the muck out as good as possible and then wash the bricks again the remove the rest.

if the muck is too hard for a toothpick, use a metal needle or a very thin screwdriver - but only do this if you can't avoid because you might be scratching/damaging the blocks (wich shouldn't be so problematic to the inner- and underside, but anyway you should avoid it).