i used rubbing alcohol when i cleaned out my pipe, it got hte shit off there really well. I used to think it had a smoky glass design or something, but it turned out that it was all gross resin build up (it was a used pipe). The only problem was that unbeknownst to me, the carb had broke sometime agao, and been glued back on, and the rubbing alcohol took out the glue too, so my carb fell out.
Just try using some warm/hot water, and maybe a tiny bit of soap, but rubbing alcohol works bestest!