Solder wire can often include some flux in the core and solder paste usually uses flux in the binder. Extra flux can definitely help in a situation where you are getting poor flow between parts. I was doing some soldering earlier today that was going nowhere until I grabbed a bottle of flux. I try to use a fan or use other ventilation when using flux (or soldering in general). If you do a lot of soldering there are smoke absorbers (fan with a filter) that help suck the air away from you.