No, these carbs are not typically "junk"---however---in your case, it sounds like there may either be a metering rod problem, or it's just out of adjustment. These aren't performance carbs, so usually they do OK on fuel usage. A good, repeat good, quadrajet will do pretty good on fuel AND performance if set up and used properly. You mention that it spurts black stuff when started up. That's probably because it's leaking down while setting idle for a long time without being started. Sounds like a metering rod issue. This is most likely because one of the two (maybe both) is not seated properly inside the float bowl. It could be that they aren't set properly in the round brass apparatus. Or, it coud be that the thing is simply worn out. It would take inspection to determine the real cause. These carbs are pretty simple, and doesn't take a lot to repair them. Good luck and I hope this helped.