You only smoke bowl resin after months of smoking weed out of it (preferably dank dro) so all the tar and resin accumulate and it will actually form like a ball of resin right below where you pack it. All those times when small pieces fell through, and when you take that last hit and sometimes suck the weed through (I dont use screens) all of that adds up and if your lucky you'll have a nice little smoke session. I've literally hit my bowl 12 times and got giant fucking rips off it and im fucking blasted atm
Dude, I was about to make a post that said the same thing. When I read your post I started l burst out laughing. I am currently high as shit from smoking some resin in the same situation as you. I bought a new bong when at the beginning of summer and just scraped some in a time of need. I probably have enough resin for a long time.
However, the smoke is harsh. But I don't think it's so bad. I'm a science major (not biology though). It seems like anything that would stick to your pieces to make resin would be a pretty even mixture as what is actually in smoke. I also have a vaporizer and gold resin builds up very quickly there, which is pure THC basically. I can't think of why THC, combined with the other molecules in smoke that you're already inhaling, wouldn't be in equal proportions in the resin.
Just because it's black doesn't necessarily make it horrible, although it's probably not great. Mine has chunks of weed in it though so that is pretty awesome.