When anyone around where I live refers to resin, they are speaking of the stuff that you get from your pipe when you clean it out. Those without much pot would save this, let it get somewhat unsticky and then smoke that. They did not add it to a joint...if they had am joint they would be smoking that.
If you are speaking about hash, that is entirely different. However, I do not add hash to joints. I love to smoke it on its own. It has a flavor that I love and would get lost in the odor of the cannabis it is contained in. And that makes for quite a strong joint. I like to smoke concentrated by themselves.
Bubble hash is extremely easy and safe to make....but you do need bud or great trim.