My own experience is that I got a rough "lava rock" type look to the solder when I had insufficient heat. My first soldering attempts were made with a 6" long butane torch and it took about 5 minutes to heat the joint sufficiently. Then after I dropped a pipe wrench on my torch I couldn't get a decent looking joint at all. The solder would tend to kind of glob on.
I got a new mapp gas torch and it made a huge difference, only about 30 seconds to heat the joint sufficiently and the solder would wick right in. I noticed that you said in an earlier message that you remove the heat when you start applying the solder. This could allow the temperature of the copper pipes to fall and lead to the rough finish you're observing. (Copper is an excellent conductor of heat so if you remove the torch I'd expect the temperature to fall fairly quickly as the heat spreads out down the pipe.) I continue to apply heat towards the inside of the joint until the solder wicks.