glow plugs 300tdi

hi

just changed my glow plugs on me 96 300 tdi and the first one nearest the fan belt was black with dry soot on it but the rest where black and very wet with like a black sludge on them the very back cylinder was the worst what does this mean or is it normal, my haynes manual is crap it dont mention much about glow plugs.
many thanks
ginger

sounds pretty normal to me , normal black and sooty, the other stuff is probably what has run down in injector mounting from outside of engine JMHO