I've noticed that too. In chicago atleast, the brown powder is almost always better than the white shit that's cut with those baby laxatives. God, I can remember days when I could go without shooting up for hours yet still not be able to get away from that smell, it felt like it was seeping through my pores. And since i had an associatio of it with dope, it always made me want to get high. It would happen at the weirdest times, while I was walking somewhere, or waiting in line at the grocery store, I would just be able to smell it on me, I felt like I was radiating dope, I probably was.
In chi as with anywhere else, if you don;t know who you're going to(and even if you do sometimes) it's always a gamble, you could get the shit, or you could get shit. Luckily, I usually found there was a pretty high ratio of good bags to bad ones, and even if through trial and error(i've completely stumbled on some great dope in my time) you quickly figure out which spots are actually trying to run a business and are worth shit. I know how much it sucks to not be able to find good dope. Good luck, and just remember it's out there, someone has it, and they probably wanna sell it to you too, you just gotta go where the dope is and find them...
jr0k