not much...i think the heat or whatever from a lighter/match kills any germs, and id rather not have it soaking in alcohol or any other abrasive chemicals...

plus, i do (sadly) end up smoking resin now and again...

my bong and pipe surprisingly dont get that dirty, or that much resin built up in them...dunno why. I find that organic weed produces much less resin than "hydro" or stuff grown with a lot of weird fertilizers. Maybe cuz those have a lot of excess cellulose and shit, because they are all beefed up to be big heavy buds.